spend at least one or two days a week working your legs. Try squats, leg presses and dead lift. Make sure someone shows you the proper form or you can get hurt. Build your legs and the rest of you will follow.
heh u sound exactly like me.. im really skinny.. but i find my self stronger than what people would think.. but unlike u i need to keep my weight at 125 cuz taht wat i wrestling this year ^_^