How do I tell my friend that I like him?

This guy and I have known each other since Kindergarten and we used to be really good friends, until I moved in the third grade. I didn't move far so we saw each other every once in a while but we never were really close again. We are now both Juniors in high school, and about a year and a half ago I started attending the church that he goes to. He was the only person there that I knew so he talked to me and since then we've become pretty good friends again. I now have discovered that I like him and I don't know what to do. I've never been in any kind of relationship before, and he only has once. I tried flirting, but I don't really know if I'm doing it right. Please help me figure out what to do without ruining our friendship! By the way he's 17 and I'm 16.

Thanks