You can use starting off, two pound hand weights. Hold one in your hand, hold you arm up so that your elbow is facing forward Then you pull your hand back to you shoulder like you are trying to touch the top of your shoulder. It seems like a small thing to do but reps is the key. Start off by doing at least ten or fifteen twice a day. There are others. If I am not mistaken, you can stand up bend at the waist forward with the weight in your hand. Raise it up like you are pulling something up from the floor to you waist. That works that part of the arm if I am not mistaken. You can look exercises up online.

I tell you what..why don't you ask 02 which exercises will help the most....He works out and he will know the exact muscle group to work.