Please don't panic by seeing so much buttons. When I first opened Unreal Editor I was scared off seeing so much buttons and thought that this work is only meant for pros. But now I'm a medium/advanced Unreal Editor mapper, so even I can learn editing :). If you just take your time and do some tutorials you will see that mapping is not as difficult as you think. Actually, the most important thing in making maps is your imagination (this is my personal problem, I have a lack of imagination). But I will explain the buttons we use in this tutorial of course. First of all, close or minimize the texture window which blocks your view, we don't need it for now.

Now you see the four view ports: The top, front, side and perspective view.
For the people who don't know how to navigate, here's a brief explanation of how to move around the view ports. In the 2D view ports (top/front/side) you can move the view by keeping pressed the left mouse button and move the mouse at the same time.
To zoom in and out, you need to press both left and right mouse button and move the mouse. People who have a wheel on their mouse can use it to zoom in and out.
In the perspective view you have to press the LMB (Left Mouse Button) and move the mouse forwards/backwards to move forwards/backwards. If you just press the LMB and move the mouse to the right/left you can turn right/left in the 3D-view. To go up and down you have to press both LMB and RMB and move the mouse up and down. And if you press the RMB only and move the mouse you can look up and down.
These are the main movements you make during editing. So practice a little bit in the empty area to get used to it.

If you're thinking: "What the hell is that eye staring at me in the 2D viewports?" Just relax it's the camera, the red arrow points at the direction the camera is looking at (in the 3D viewport).

One thing you also have to know is that keyboard-mouse combinations are also very important in editing. For example a simple one: selection of multiple objects/surfaces occurs by holding ctrl and clicking the desired objects/surfaces. If we need such a combination I will mention that.

If you practiced a little bit the navigation part, we can start building the first room!

Rightclick the cube button to set the height, width and breadth of the room. You see a window like this:

We want a room with height: 256 width: 1024 breadth: 1024. That's enough space to move around. Try to keep your sizes even (4, 8, 16, 32,64, 128, 256 and so on), it just makes it easier to align to the grid. A height of 256 units is the normal height for a room so keep that in mind. Fill in the values in the appropriate field and click "Build". Now you will see in each view port a red wire frame of the room you just built. This red wire frame is called a brush.
Now you don't have a room yet, you just created the brush. To get a room you have to subtract it from the world.

You have to think that the initial "empty" world you begin with is SOLID, so you can subtract things from it. In the subtracted areas you can then ADD other things. You have to know this to make it easier for you to know when you have to subtract and when to add a brush.

Let's go on with the room: To subtract it from the world click on the "subtract" button:

To make the room visible in the perspective view just click once in the perspective view. Maybe you need to move around a little bit to find it.

Saving your work regularly is important because the editor is not completely bug free, it can crash for no reason.

The textures you see now are the default textures, so we need to change them to have a nice textured room. Try to move inside the room in the perspective view (if you forgot how to move in the perspective view just scroll back in this tutorial to see how to do it).
So we have 4 walls a floor and a ceiling to texture. Remember the window we closed in the beginning because it blocked our view? That window was the texture window which allows you to load a texture package and choose a texture.

The textures for UT2003 are stored in "UTX" files which are in the "C:\UT2003\Textures" directory. Each package has an own texture style. You choose a package depending on what style your map will be (Industrial? Alien style?).

To get the texture browser back just click on the texture button which you will find just below the main menu of the unreal editor.

Click File on the Texture Browser and click on Open, or simply click on the Open icon to browse the texture packages. It will be easy for you to choose the same textures as I to compare your results with mine when you're finished.
I like the "Shiptech.utx" package, these textures have a futuristic style. When you open this package the textures are loaded and you can see them in the texture browser. When you take a quick look at them you can see they differ in size. Some textures are 1024x1024 pixels and some are 512x512 pixels or even less. In the texturebrowser you can see two fields, the upper one is the name of the package:"shiptech" and the lower one has the different categories to which the textures belong. So if you choose "walls" from that dropdown menu the browser shows all textures in the "shiptech" package that are meant for wall texturing. You can of course apply a wall texture to a floor, but that is not logical:).

Let's start texturing the floor. Go to the "floors" section and choose the texture called "Texture floor2b [DXT1]" You can see that the texture is 1024x 1024 pixels so it will fit exactly on our floor which is 1024x1024 units. You can adjust the size of each texture, but I will discuss that later on. For now we just keep it simple.

To apply the texture to the floor just leftclick the floor surface and it will become blue, which indicates that the surface is selected (keep that in mind). When you have selected a surface just go back to the texture browser and click on the "Texture floor2b [DXT1]".Now the texture is applied to the floor surface.
Let's continue by texturing the walls. We have four walls that we want to texture, you can texture them one by one, but why do that if it is possible to texture them all at once :P . To select all four walls just hold ctrl and select the four walls with the left mouse button till they are all blue. If you managed to select them all just do the same as with the floor but with another texture. I chose: "Texture wal36cs [DXT1]". Go to the dropdown menu which is now on "floors" and choose the "walls" section, there's where you can find the texture I used for the walls. Now you will probably notice that the texture is too big to fit the height of our room. Our room has a height of 256 units and the texture has a height of 1024. Now it's time to adjust the size of the texture (which is called scaling).
If we want the texture to fit the height of our wall we have to scale it down 4 times. Select all walls now (you know how to do this, right?) and click your right mouse button on one of the walls from the menu choose: "surface properties" (you can also press F5 to go into the surface properties).

Here you can adjust various surface properties, but for now we just need to scale down a texture. You do this by first clicking the "Pan/rot/scale" tab. Under this tab you can pan a texture, rotate and scale it. We will do a simple scaling by choosing one of the scaling numbers in the dropdown menu. We wanted to scale it 4 times down, so that means we choose "0,25". If we choose "0,5" we would scale it down a half time, that's not what we want. You can also adjust the size in the U and V directions (horizontal and vertical). But it is not necessary for now. When you did this click on "apply" and you can see in the perspective view that the scaling is applied.
Now we only need to texture the ceiling. Select the ceiling and go to the texture browser and choose the "cel03cs" texture for the ceiling. Now we textured our room and it looks like this (I already put the lights in this picture):

What do we need more to make a map playable? Indeed: Lights, otherwise you will play in a dark box. And of course a place where a player can start playing, this is called a player start (spawnpoint).
Let's first add the lights. We will add 5 lights: one in each upper corner and one in the middle of the map. That should be enough to see something, while you're playing.

Adding a light is simple: just rightclick on the place you want the light to be and choose "add light here" from the menu that appears. When you added the light you can see an icon that represents the light. You can move the light by selecting it (like all other objects) and move it to the place you wanted it to be. If you select a light it will turn green which indicates it's selected. We could adjust the properties of each light by right clicking it and choose "light properties" but this will cover a whole tutorial, because there are many things you can adjust. I will write a separate tutorial on this subject later on.

Now let's add a player start. Right click on the place you want the player start to be and choose "add player start here". I suggest placing a player start in one of the corners (close to the floor of course). You can add more if you want to let other players spawn at these points.
The player start symbol is a joystick with a red arrow which points at the direction you are looking at if you start playing/respawn. Make sure the arrow is not pointing at the wall. You can rotate it by selecting it and hold CTRL and RightMouse button and move sideways to rotate. You can use this combination of CTRL and RMB for rotating other objects, so try to remember this.

It is now time to finish up your room, with a very important step called "rebuilding". If you do this, the engine calculates various things like light intensity, shadows and many other geometrical things. You have to do this to see a map the way you meant it to be. So when you make a map never forget to rebuild (and then save). You can rebuild by selecting "build all" from the "build" menu or by pressing F8 and then click "build".

If you save a map it will be saved by default in the "C:\UT2003\Maps" folder. If you want to play your level press CTRL+P and UT2003 will load your map. You can also do this by selecting "play level" in the build menu. If you want your level to appear in the menu inside UT2003 then you have to call it "DM-something" so that UT2003 recognizes it as a deatchmatch level.

That's it for now. I know it's a pretty simple map, but that's how everyone begins editing. I will cover in next tutorials how to place weapons, pickups, adjust light properties, make lifts/doors move and how to make a more complicated map than just one room.