Liver and fava beans.
Seriously, though, it's great that you're asking. This shows you're serious about doing it right and making sure you're not wasting your time lifting and then giving your body nothing to build upon.
I am no nutritionist, not a doctor, not Oprah, not much of anything really, but here's what I came up with for my own son after doing some research.
For My Son (just turned 19):
To build muscle during his summer workouts, he needs to consume between 2800-3000 calories a day, spread over 6 meals, each about 3 hours apart, and in the following ratios: 50% protein, 30% carbs, 20% healthy fats. These ratios are for building muscle, not necessarily for endurance, so after his summer training he'll need to bring the carbs back up but still get enough protein to maintain his gains.
I just did a quick google and found this straightforward document which can help you figure things out:
http://www.extension.umn.edu/family/W00030.pdf(you will notice, however, that for my son I have researched a much higher protein % than recommended here - just personal choice based on other things I've read - and besides, my son is thin as a rail - he needs a little bulk and is working out hard.
Good luck to you!!