If you want to learn the basics of modding I segust;
-If you have a backround in modding outher games(like me) and are just starting stalker modding, jump into the deep end so to speak, learn by trying, make a mod help me out with a mod
-If you have no expearence modding, learn from a slimpler game such as "Jurassic Park: Trespasser" thats where I started, than go from there.
-Go talk, learn, and help on the mini-modding thread.
-Try on your own. Start a mod or fix for PS. For example Im making a mini-mod for PS 1.1, Im addding a trader and balancing them out. (if you want to help your welcome)