Check out Limited Mobility Lifestyle center! www.sparkpeople.com/resource/lifestyle_cen
Have you been to your doctor? The first, most important step for you right now is to go and get clearance for exercise before you start. Remember that losing weight is 80% nutrition, and only 20% exercise, but moving will help your arthritis. Not only have studies shown that exercise improves symptoms, anecdotally I can confirm it has helped me a lot!