Pretty much just eat like you normally do. (assuming you're already eating a healthful diet)
Take lots of water and a good supply of snacks with you on rides. I like Clif Shot Blox and ziplock bags of cheddar cheese and pecans. Everyone has their own perfect fuel on the bike, it takes some experimenting but you will find yours, too!
I eat about every half hour or so while riding, and generally have something like a V-8 and some crackers and cheese after if I don't have a meal soon. Again, how often you eat during a ride and how much you eat is a very personal thing and it will take a bit of trial and error to find your own plan.
Better to bring too much food on a ride than not enough! 
If you start having trouble, it can be well worth it to do a consult with a nutritionist. They can help you figure out what to eat and when during rides.
"If Americans want to live the American Dream, they should go to Denmark." - Richard Wilkinson