You should eat something within 2 hours of your workout. This will replenish the fuel, fluid, vitmins, minerals, and all the other building blocks that your body needs to perform at a high level on a daily basis.
It is particularly important after competition to eat a good meal. Competition involves pushing yourself both physically and mentally to perform at your absolute best. In order to recover and be able to train again the next day at a high level, you must make sure you give your body all the feul that it needs.
Robert Haas in his book Eat to Win outlines a post exercise meal that I feel works very well:
Eating a meal based on this chart will provide all the proper nutrients needed for recovery. If you are not able to eat within 2 hours of your competition, eat something else such as fruit or a granola bar or energy drink to tide you over until you can eat a real meal.
-Coach Chuck