Body building exercises and tips please?

I'm 13 , 5'8'' (175 cms) and 137 pounds (62 kgs) and I want to build up my body, especially my arms and chest.This past 2 months I gained 22 lbs, because I was very skinny so I started to workou a bit and ate a lot more. I practise basketball every Monday Wednesday and Friday.I had no equipment home and no gyms around so I lifted bottles and stuff and I made pushups. Yesterday I bought a pair of 9 lbs(4 kgs) dumbbells and I improvised a bench with two chairs and pillows so now I have some "equipment" at home. Please give me some exercises so I can build my arms and chest. *I want to focus more on my chest