Yeah seriously man if you're having this much trouble with it you need to stop posting on ATOT and discuss with a teacher/professor, TA, fellow student, etc. So many people have already tried to explain this to you it should be obvious that you can't understand this by reading posts on a forum. Set up some one on one time with an instructor and have them explain things to you, ask questions, have them explain in other ways if you still aren't getting it. If you're in college you are paying good money for them to teach you this stuff, so take advantage of it.
EDIT: TecHNooB good luck. He's already made 2 (3?) threads on this, many people have already tried to help him. It's not a specific problem but a concept he's having trouble with.