For the first two days or so, stick to soft foods. Before long, you'll be able to chew normally. However, you'll need to protect your orthodontic appliances when you eat for as long as you're wearing braces.
Foods to avoic include, but are not limited to:
CHEWY FOODS - bagels, hard rolls, pizza crust
CRUNCHY FOODS - ice, popcorn kernals, hard chips
STICKY FOODS - gum and chewy candy
HARD FOODS - nuts, candy, hard pretzels
FOODS YOU HAVE TO BITE IN TO - apples, corn on the cob, carrots (if foods are cut up they will be fine to eat)