I have spinal stenosis and am a bit overweight, can you tell me some easy excersises i can do that won't kill my back.

Yes: It is far better to have a physical therapist examine you and work hand in hand to discern your capacities, but suggest you focus on stretching, postural relief, and perhaps learn some of the mckenzie back exercise protocol. Do believe, that you might benefit from weight loss also, as that would be palliative.

See below: Probably the best would be pool aerobics; the water supports your weight & there's minimal impact on ankles, knees, hips, back. Provides excellent work-out so lose lbs (as long as u eat sensibly too) & is fun & sociable. Advise instructor of your back problem so s/he can advise u of any movements to avoid. Have fun.