Put your arms behind your body & place your hands on a solid object. Say a chair against the wall or a large planter box & lower your body down by your arms with your knees bent & then back up. Do it regularly bout 10 at a time but start off with 2 & work your way up. That should help.
Push ups, weights and pull ups. Also chair dips(p90x) grab a chair and seat on the edge of it, put your hands on each side of the chair. Basically you go up and down just your hands on The chair with yout legs extended or at 90 angle and dip. If you dont understand my instructions search p90x chair dips
Biceps: Bench press Triceps : Dips Why you need to workout triceps ? Because it takes up2/3 of your arm and if you don't workout your triceps your arms will never get that big. Focus on triceps more than biceps .