HELP ME ABOUT COLLEGE STUFF (University of Illinois at C)?

Ok, first of all, I'm going to be junior this year. And I realize that I have to work harder now. I mean like "this is it". But I don't know anything about going to college. What do I have to have? High grades? Please give me advice. I will work hardest. And tell me about ACT/PSAT whatever. And what do I have to read to p those test. I just really want to do it! I am motivated now! I would appreciate any advice! And btw, how do I get scholarships? Help me to be smart! ^_^ THANK YOU!