To be honest your best bet is to search the previous threads considering this has been asked a dozen times. Its faster than asking everyone to repost.
That being said here are some tips:
As said above - eat every 2-3 hours. This will increase your metabolism. Do not eat large meals, but 5-6 smaller meals.
Try to seperate your meals as Protein and Fats, and Protein and carbs. Do not eat a high amount of Fats and carbs in the same meal. Only one can be used for energy and the other will be stored as fat.
Mentioning fats, be sure to get at least 20-25% of your diets in healthy fats. These can be from sources such as: Macadamia nuts, Flax Seed, Flax oil, Fish Oil,
Natural Peanut butter, etc. I personally take at least a tbs of flax seed oil a day.
Make sure the majority of your carbs are complex. These come from sources such as: SWEET potatoes, oatmeal/oatbran, WHOLE GRAIN Bread, brown/wild rice, etc. Stay away from white foods and enriched food. Sugary carbs are worse than fat as they cause a serious insulin spike and promote fat storage. They should really only be consumed post workout. The exception is fruits. Fruits do not require insulin to metabolise so eat up =)
Fiber is a key to a properly working
digestive system, make sure you eat 25-30g of fiber a day.
Water, water, water. Drink at least 8 glasses of water a day and more if possible. Stay away from cokes (Drink diet if you have to have something) and other sugary drinks (For reasons mentioned above).
Remember, you are what you eat. If you eat junk, your body is going to be junk. Welcome to the boards!