keep it simple b/c you're young and need to have fun. Basically do this:
Do not consume sugars in any form except for 40g's of dextrose post workout along with ~30g whey in a shake.
Do not consume any white flour products, including but not limited to: white rice, white bread, pasta (unless it's whole wheat pasta), and pretty much all pastries. Keep consumption of whole wheat products high.
Aim to get a high quality protein source in each meal (i.e. meat) Make sure that if these meals have a significant amount of fat that you don't combine them with white flour or sugary products.
Drink Green tea several times daily, or better yet, pick up some green tea extract. You can get the metabolic rate increases of a diet pill without the stimulants.
If you are prone to being puffy at all, drop dairy and see how your body reacts. Some people can expose their six pack just by dropping sodium intake.
Whey protein only after workouts. If you need to substitute a shake for a meal somewhere, try to get a blend of proteins as whey is going to absorb too quickly leaving your body with a void to fill for the nxt 2-3 hrs.
Space all your meals to be about 2.5 hours apart. Several small meals is the best way to maximize nutrient absorbtion, stabilize blood glucose levels, and keep your metabolism moving at its most efficient rate.
As for exercises, just remember. Your six pack is there, you just gotta expose it. So without proper diet, you can do sit-ups till you're blue and it's still not gonna come out. "six packs are made in the kitchen, not the gym" To accelerate the process. Go for a 5 mile run in the morning before you eat and before school 2-3x/ week. This will ensure that your glycogen levels are at their lowest point of the day and maximize the usage of fat for energy.
You're in high school.. If you have to drink, try not to eat food while drinking. Alcohol has some nasty effects on nutrient partitioning, conveniently enough it often induces munchies...
Lastly, read as much as you can on this board. If you keep up with the posts on here daily, you will be on top of your sh*t in no time. Post up all u need with?'s. there's always someone here to answer them.
good luck