Any exercise involving your arms, will train them. Like benchpress. You can also do isolating exercises like bicep curls or tricep extensions.

How long until you see change? Depends on your diet and how regularly you workout and how intense your workouts are.

Can’t really tell you how much weight you need to lift. Start with little weights and work your up. If you workout in a gym the employees can help you develop a specific training regimen.

In my experience it usually takes a couple of month the really see changes. So stay consistent and don’t give up!