If you concentrate on your diet first you should be able to lose a bit of weight before you start exercising again. I've found an easy way to start eating healthier is to mentally divide your plate up. Half should be veggies, one quarter starchy carbs and the remaining quarter protein and healthy fats. Or you could count calories with Calorie King (http://www.calorieking.com.au
). If you sign up to Calorie King (which is free) you can work out how many calories you can have per day, plus you have the choice of entering your own food or following their pre-set menus. And there are many people on this forum using meal replacement plans as well which could be an option for you. There are many methods of addressing your diet and I'm sure you'll find one that fits your needs!
As to exercise, I'd recommend talking to your doctor and finding out exactly what is safe for you to do and get a timeline for when you can start doing more strenuous exercise. Don't attempt to do anything until you've had your doctor's okay. Given that a c-section is a serious procedure that cuts through so many layers of skin and muscle you really don't want to try too much too soon. If he's said walking's okay then stick to walking for the time being.
Good luck and congrats on the new baby!