I want to go to military school, please read!?

Ok so I want to join the military after high school. This year I will be a freshman, but I want to attenend military school as a sophmore because this year I am a cheerleader. How could I convince my parents to allow this? I live in Texas and hope to either join the Marine Corps or Navy. Do you know of any good military school in Texas? Please help I want this more than anything.