Can someone explain the entire fraternity thing to me? I'm a bit confused?

I know fraternity's are greek organizations and all that stuff but how do I choose one? Do I pick one or do they pick you? What is rush week? And what's hazing? anyway my friends brother is an ATO and he wants me to pledge ATO and from what i hear i like it. But do they have to pick me or do i pick them and how do i pledge? do i have to drink a lot or something like that? sorry i know i sound lame. i don't want to ask my friends brother because im afraid he wouldn't want me to join anymore or something if i sound like a loser asking him all this stuff. If you are in a frat can you give me your person rush experience and all that too? thanks