the main thing I cant understand at this point is the following:
Lets say I have a random person and I want to make their facial skin tone the same as a character in the movie Avatar. I just dont get how to do this. Any help would be wonderful
Welcome Avesher!
Dang, there are a lot of ways to change skin color.
Here is a tutorial from Howard at Ice Flow that is sort of basic
http://www.wonderhowto.com/how-to-change-skin-tone-photoshop-215933/Photoshop program methods are generally complex. Some of the cheaper programs like ARCSoft Photo Expression or Photo Impact or Photo Explosion have a one or two click option to change skin color. So it is always handy to have some of the smaller programs for the fast change stuff. You can always go in with photoshop a bit later to detal and highlight with the airbrush or various brushes.