Intro.
This tutorial/information document is mainly for new, new beginners to flash. I have just compiled a bunch of introductory terms and definitions about the program for people who are just starting off.

The bare essentials...
Flash is a vector-based animation program. Vectors are different than pixels, as they are often smaller in filesize (when simple) and can be scaled with no blurriness or pixelation. They are mainly use for cartoons and illustrations. In Flash, you have two main sections--a stage and a timeline. The stage is where all the graphics and other things are place, like a layout of the final movie. The timeline contains frames that show how things progressively change on the stage. When exported to swf, or flash movie format, all the audience sees is the final movie. The only way to edit a flash file/movie is if you have the .fla file.

Stage Stuff
Here are somethings that you can put onto the stage and work with:
Vector Drawings: You can use the drawing tools to create you own graphics, or import them (ctrl+r). These are non-grouped, which mean every section of different color in a graphic is speperately selectable. Only broken drawings can be shape tweened
Graphics-Symbol: In flash, sometimes you re-use images more than once. To save filesize, we are able to convert a drawing to a symbol, which is stored in the library. Basically, this allows flash to grab the same image and reuse it again. only symbols can be motion tweened. To convert anything to a symbol, select it and press f8, and choose what type of symbol you want it to be.
Buttons-Symbol: Buttons are also symbols, but within the symbol are 4 frames. One for when it's sitting there, one for when the mouse is over it, one for when it is pressed, and another to define what area will activate it. Only buttons have individual mouse actions, and change the cursor to the common "hand link" icon.
Movieclips-Symbol: Movieclips are like mini-movies, that have as many frames within them as you want, and run individually of the main timeline. They have tons of other features, but check out another tutorial on movieclips.
Bitmaps: You can import jpgs and bmps into flash, and even convert them to symbols so you can animate them etc.
Text: You can have any text in your flash movie, and all fonts, no matter if the other computer doesn't have it, will show properly. You can covert text to symbols too. Dynamic textfields are more advanced, where the use types in them.
Drawing: There are many drawing tools-pen, paintbrush, etc. If you click on a raw graphic (broken, not a symbol) you can smooth its edges or sharpen then (under modify)

Timeline Stuff
Frame: Like any frame in animation. Shows progression of movie
Layers: The different rows of frames. Symbols on top layers appear over the ones on lower layers.
Key Frame: Create one by pressing f6. Keyframes mark points on a layer's timeline where change happens. Maybe a symbol is moved, or something is added. When you tween, you must have two keyframes. The frames inbetween interpolate the changed of an object.
Tweening: Creates movement steps between 2 keyframes to make the transition between the two an animation. Look at the tutorial on motion tweening for more info.
Shape tweens: Signified by green block of frames. Like motion tween, but used for broken graphics. Has more of a morphing effect, usually being used for an image to turn into another.
Locked Layer: Locks layer, so nothing on it or on stage layer to be selected.
Masking :Two layers, where one acts as a mask, the other being under the maks. See the masking tutorial for more info.
Motion Guide Layer: A layer containing a path (made from a line) that another symbol on another layer follows. See the tutorial on motion paths for more info.

Other Stuff
Scenes: Scenes divide up the main movie.
Library: A storage area where symbols are put. To open press ctrl+L. To take out a symbol, simply drag it the library window onto the stage. Using the library to stor symbols that are used more than once decreases filesize.
Magnet: Also called "snap" used to snap symbols onto motion paths, draw straight lines, connect lines when being drawn etc. I usually disable it, because most of the time it's a pain in the ass.
Copy+Paste: Note that you can copy graphics and frames. Frames are pasted on the timeline (and you must do copy frames) and regular paste is used for pasting stuff on the stage.
Frames Panel: An important panel, allowing you to label frames, adjust tweeing etc. Access with crtl+F
Instance Panel: Allows you to edit symbols: their tint, alpha level, instance names, definiton. Access with crtl+F

Publishing
There are three main ways of publishing. You can test the scene of a movie, which exports the scene you are in and plays it in the preview mode of flash. (alt+crtl+enter). Testing the whole movie exports the whole movie (ctrl+enter) Finally, when you go to publish, it exports your whole movie but also puts it into an html document. See the publishing tutorial for more help.

In the end
At first the program may seem confusing, scary and daunting. But don't give up. It won't take much time at all, depending on your experience with other programs on how long it takes for you to learn to use flash efficiently and well. What has been mentioned here is just scratching the surface. Take a look at other tutorials for more info on certain sections, and just play around with it a lot. This was just to give and newcomers an idea about what everything is. I wish you good luck, and happy flashing!:)