1) Eat a regular, balanced diet but cut out the vast majority of junk food (soda, candy , chips, fast food, etc...)
2) Cut your current portion sizes in half. Basically you should be hungry, but not starving by your next meal.
3) Drink lots of water.
This should get you started and shouldn't be too drastic of a diet change. Once you get used to it you will want to modify your diet again to eat smaller portions more frequently (5-7 times per day). I've seen alot of posts in this site on the specifics.
Good luck with the training. BYW, Intermission is right on the girl!!!