As Patrick mentioned, Entering the Zone is an excellent book. I'd also recommend The Paleo Diet by Dr. Cordain and Natural Hormonal Enhancement by Rob Faigin (visit www.extique.com
). Those 3 books will give you plenty of information ... and hopefully not too much. They are similar in many respects.
If you are not into reading and just want the basics, the CrossFit eating philosophy is laid out nicely on page 8 of "Crossfit Foundations". Just follow the links from the main page to "What is Crossfit?" and you'll find the link on the right hand side of that page.
Good luck and have fun!