It is quite commonly though the most effective exercise to remove excess body fat is aerobic. I recommend you either but an aerobic or dancing exercise DVD and practice at home until you can build up enough stamina and confidence to join a regular class.
It is essential you do these exercises 3 or 4 times a week and that at least one of these sessions are long in duration (40mins +). It's perfectly fine for you to "work up" to this level, all weight loss takes time.
I would augment this with a small amount of crunches and sit ups at the end of each routine as this will help you tone the muscles in your abdomen.
Combine tghis with a balanced diet, try to eat a little smaller portions an possible a fat binding pill, only a natural ingrediant one not a chemical weight loss pill, something like the proactol fat binder and simply work at it!
Good luck!