To install a mod on to your (SWKOTR) Game if you have steam.
It is farliy easy to get the hang of.
Step one: go to your C:\Program Files (x86)\Steam\steamapps\common\swkotor.
Step two: open your "override" folder, it should be under the rims folder, and above the movies folder. if it isn't there just make one. and if you don't know how to that, im going to tell now.... RIGHT CLICK AND THEN MAKE A NEW FOLDER.... and if you still don't know how to make a folder you shouldn't be using a computer.
Step Three: Download a Mod from Moddb.com or Filefront.com thats what i use.
Step Four: when the mod is done downloading Copy and paste that files into your "Override" folder and your mod is good to go.
P.S. You should read the description of the mod when you download just incase you need a cheat to activate the mod.