We've got a whole nutrition part of the site. CHeck it out.
Those were two things that helped me get started.
Simply eat good food at every meal and write down everyting you eat and drink each day for two weeks. Weigh yourself before you start and after the two weeks and see what happened.
Each day, put what you ate in a food calculator like fitday.com and get your macros calculated for you.
Average it to see what your normal food intake and macros are. Compare it to your weight and make changes based on what you want to do.
General rule of thumb is to eat 1 gram protein for every lb of body weight, so for you at least average 125 g protein every day. If you're doing that, everything else is likely to fall into place.
That said, Swede is right. You're young and shouldn't really worry about macros or calorie limits or specific foods too much. Eat 125 or more grams of protein, don't skip meals and don't eat crap very often and do your workouts, and everything will fall into place. Track it for a while to get a sense of what's working, then refine it as you go along.