Hi Meg and welcome to 3FC =)
You might find others coping with back pain and other issues under Dieting with Obstacles.
There are definitely still ways to manage weight even if you aren't able to do as much physically as you'd wish. The most important thing is to manage calorie intake. Eat fewer calories than you are expending, and you'll lose weight.
Even with that said, most people here recognize that it's not
exactly that easy. The idea is simple, but in application it can get tricky. We've all found different methods of managing food. Some people follow a specific plan, some people count calories or carbs, there are a myriad of ways that are working for different people.
Look around, see if a certain method speaks to you or if there's a system out there that you know would fit your lifestyle.
You can definitely do this
Hope to see you around the boards!