Congratulations on making progress! The simplest, and some of the most effective upper body exercises are: pushups, pullups (and Australian pullups, google it if you need to), and dips. I'm imagining you may have trouble doing pullups. Dips may also be difficult. If so, you can try doing pushups with your hands closer together than normal. this hits the triceps more.
If you don't have access to a gym (and even if you do), body weight exercises are the first thing to try.
If you can't do pullups, you can use machines at a gym to simulate the movement with less resistance (lat pulls, or assisted pullups). Dumbbells can be used to target delts, which are hard to get to w/o weights (although I have used milk jugs filled with rocks and water as a shoddy substitute).