With a c-section it is good to take it slow at first. Make sure your incision is totally healed. I had a c-section with my daughter 10-months ago, and I know the first few workouts are hard! I waited to workout until my doctor gave me permission at 8-weeks.
I would start by taking your baby for a walk in the stroller everyday (or even twice a day). If you have a double stroller, you can take your 22-month old and baby at the same time. Each walk you should focus on going a little faster.
To really speed up your weight loss you will want to do some strength training as well. You can do this at home with workout videos while your children nap, or you could try a class. I like www.collagevideo.com because you can watch a few minutes of video to see if you will like it.
I do Baby Boot Camp classes which are great because you bring your baby (and/or toddler)to class in a stroller and that takes care of the issue of what to do with the kids while you workout. We do cardio and strength training in each class, so it is very effective.
You can check to see if there are any classes in your area (www.babybootcamp.com), or you could also check with your local gyms/ymca to see what they offer moms (a lot of places have a nursery).
I know that it is so hard to get motivated to workout after having kids because you are just so tired all the time. Good luck finding something that works for you!