What's an effective arm workout with dumbbells?

Hi, I'm 14, 5'8, around 140 pounds. I recently bought some 10 pound dumbbells in order to bulk up a little. I want to bulk because I swim and run and being stronger would definitely be an advantage. Don't suggest not to workout because I know that 10 pounds is the equivalent of a pencil in bodybuilding, so it's not going to stunt my growth. Anyway, I'm looking to workout my upper body, but MOSTLY get bigger arms (so that would be working mainly on biceps and triceps?) I would appreciate if someone gave me some exercises and if possible repetitions. My endurance is pretty good, but my left arm is really weak. Thanks for any help!