New to diet and exercise

I think i waited a little too long to get in the fitness game, I have a fusion of c5-c7 in my neck with one plate holding the 3 discs together, have had 2 arthroscopic knee surgeries have never dieted, The state of y body limits what i can do. I'd like to eventually try weight training but for now i do a 1 hour class called silver sneakers for the elderly and disabled twice a week, been doing it for a month, and this past monday I joined Curves as well and do 2 circuits for a total of 30 minutes of resistance machines and jogging in place followed by 15 minutes of stretching. I've switched my breakfast to either kashi go lean crisp with 1% milk or a chobani or oikos fruit on the bottom yogurt because both have high protein. I eat either the yogurt or low fat cottage cheese for lunch with some fruit, usually either peaches or pineapple in their own juice and occasionally salsa with it. For dinner, half my plate is green vegetables. I do still drink my morning coffee with half and half and sugar, its one indulgence i can't do without. And i have an occasional after dinner snack.