Fresh fruits and veggies (cooked and raw) and lots of protein in the form of lean meats, cheeses are excellent. Congrats on your baby!

It's tough to get on track after having a baby. I know, I lived it!!! Good for you for taking the first step.
Make sure you eat breakfast - most important meal of the day and it jump starts your metabolism. Eat six small meals during the day like this: Breakfast, snack, lunch, snack, dinner, snack. Eat lean meats like chicken with skin removed, (white meat only), fish, lean beef, cottage cheese is a really great protein also (1%) Eat lots of vegetables and at least 3 fruits per day. Avoid potatoes, white bread and sugar. Drink at least 8 glasses of water per day. Try going for a walk every day at a brisk pace for at least 30 minutes. The baby will love being outside in the stroller and will probably sleep well.
Good luck!

As you know, take it easy the first 6 weeks, I have three and my youngest is two. I'm smaller than I was before I got pregnant with my second. Try Windsor Pilates, it's low impact and won't put too much strain on your body as your trying to recover. They also recommend swimming for your joints. The obvious thing is diet, but it's tricky especially if you're nursing because you need to eat enough for the both of you. Hopefully you can figure out something that works for you since everyone's different and congratulations:)
BTW:
When you're feeling better/stronger try these videos: Zumba and Dancing With the Stars Cardio. I have them both and if you like to dance you forget you're working out.