I want to get in shape!?

I am 15 years old,male, and im 68kgs heavy.My height is 6"3.I am not so fat but i have got chubby stomach.Whenever i wear tight t-shirts it doesn't fit well and whenever i sit those layers all over my stomach can be seen easily.If i wear anything e lse i look quite thin.My body is shaped weird.Its not in V shape like most of the guys have but its shaped like an hour glass.How to lose that chubby stomach? How to bring my body in shape?