The best introduction to healthy eating is understanding the food pyramid. The concept of the food pyramid is to consume a greater amount of the ingredients at the base of the pyramid and to limit the intake of the ingredients at the top of the pyramid.
As an athlete, the concept remains the same however, it is expected that the amount consumed will be much greater. The reason for this is that an athlete is required to train for multiple hours every day and will need to exert much more energy to do so than an individual who is not an athlete. This comparison is seen in the following images below;
The key factor to remember is that moderation will always trump deprivation in the long run. A healthy lifestyle and environment should also be something you consider in conjunction with healthy eating. If you want to make improvements to your lifestyle and eating habits whether you are an athlete or not, the food pyramid is a good start and a great point of reference.