I'm not really looking to get a bodybuilder's sculpted body, just want to look more muscular than a skinny pile of bones. Since I'm at boarding school, I don't really have access to any gyms or other equipment except for a pull-up bar and a swimming pool. What kind of personal workout schedule should I follow (pull-ups, pushups, situps, etc)? I mainly want to work out my arms, chest, and abs. The only free time I have is either early in the morning or evening/night - which one is a better workout period? Also, since my food choices are pretty much settled for me, the only diet changes I can make are supplements - what kinds should I get? When it comes to protein shakes and all that, I'm pretty much clueless.

Thanks for the help!