First, you need to talk to your doctor about what you can do for weight loss. Weight loss is not about exercise; it helps, but in the end, losing weight is all about the food you eat. In order to lose weight, you need to eat less than you burn. The process is easier when you exercise (you can eat more and still lose weight) but if you don't cut calories, you're not going to lose weight no matter how much exercise you do.
So, your first step is to head to a doctor, explain what's going on, and get some advice. Then, start working on the kitchen.