I really would like to exercise away some stuff.

I've kinda got a "beer-belly," not that big, but I wouldn't mind getting rid of it, maybe get some muscles there instead.
Also, my chest is sort of flabby, I would like to get a real chest instead...if that made any sense.
And I've got a large butt, any tips on how to get a nice ass?


Please take into consideration that I'm a 17 year old guy. Thank you in advance