This belongs in the pregnancy nutrition/fitness forum.
You can eat most of the foods you ate before you became pregnant. Lots of fruits and vegetables, meats (make sure they're cooked properly), dairy, and snack on healthy things like nuts, small fruits, granola. Also drink lots of water.
You'll want to limit your contact with certain foods, such as tuna and sushi. Be careful with alcohol - either limit your intake or cut it out altogether. The same goes for smoking. Limit your caffiene intake - two cups of coffee or less a day, or a couple of sodas.
And be careful with your sugar intake. The saying "you're eating for two" does not mean you should eat twice as much. It probably won't damage your baby, but you'll have more weight to shed after your child is born.
Basically, just be smart about what you eat. You don't have to follow a strict diet, but try to keep things pretty healthy and feel free to treat yourself on occasion.
Good luck with your pregnancy! Feel free to join our discussions on the main pregnancy forum.