File                                                                        Click on file with picture to copy
New                                                                      Capture the picture with the lasso/marquee tool
determine size in inches                                           Edit - copy
determine resolution (pixels per inch)                       Click on file to paste into
                                                                               Edit - paste

To resize image (smaller or larger):               Flip or transform images:

using lasso/marquee tool, choose                             using lasso/marquee tool, choose image
    image to resize                                                        to resize
Layer                                                                      Layer
Transform                                                               Transform or Free Transform
Scale                                                                       choose desired transformation
Drag corners/sides of box to resize image                 double click in box to set
double click inside box to set size

Using the Magic Wand tool:

The magic wand tool helps to redefine an area after using the marquee tool or lasso tool to choose an image/area.  After choosing the area with lasso/marquee tool, click on the magic wand.  To add to an area, click on the pixels you want to add...the magic wand tool will choose the pixels in the area you have chosen that are the same color/value.  To eliminate areas, hold Alt and click on the area to subtract.  You can continue adding/subtracting areas to redefine the selection area.

To add areas:  click on areas with magic wand
To subtract areas:  hold down Alt while clicking on area to subtract

Layers:

A note about layers:
everytime you copy/paste an image onto your file, you will add it on a new layer.  Layers are like sheets of clear plastic that hold your image.  If you are having trouble moving or resizing a portion of your image, you may be on the wrong layer.

To view layers:
Window
Show Layers
Choose the layer you want

When it becomes convenient, you can merge layers, either in pairs or all at once.  I discourage students from merging until they are sure things are exactly where they want them to remain.  To merge 2 layers, choose the top layer of the two, and choose Layer, then Group with Previous.  To merge all layers into one, choose Layer, then Flatten Image.