Hi there! Welcome
I would suggest to just start off very slowly, watch what you eat mainly, maybe join calorieking or weight watchers or lite and easy to help count calories and keep an eye on what you're eating.
Because of your injuries I reckon you shouldn't push your body to do more than it can. Just start of with some slow easy exercising, maybe walk slowly for about 10mins a day, kick a ball slowly up and down the back yard, maybe some tai chee (sp?). Get yourself into a routine with food, and small amounts of exercise.
Alternatively, you could try using something like tony ferguson shakes to lose a lot of weight rapidly to allow yourself to exercise more or harder, and to help get some strain off your injuries.
I hope all goes well, check in with us and let us know