I am 16 years old, 5"8" 125lbs and i have been recently going to the local YMCA to workout. The only problem im having is getting a good routine/workout. i dont know what machines to do/what not to do. I am pretty skinny but i do have muscle on my arms and legs. I mainly want to get my upper body bigger. What would be a good workout plan for me to get my upper body bigger? Please include names/explanations/# of reps. Thanks for your help.