Boarding school for free??!?!?!?

Hi, I REALLY would like to go to boarding school. I've wanted to for so long! Next fall I would like to be excepted to a coed boarding school in the USA for my junior year. I'm not very picky on anything I would prefer but am not limited to nondenominational/catholic equine/volleyball. I don't mind about the dress code or anything like that, nor dorm accommodations. My parents have agreed that I can go, IF I find a way to pay tuition. My dad is a single parent, and can not afford to pay for hardly anything. I REALLY want this, but don't know how to get it with lowish grades and no money... HELP???