how do i turn on my iPhone 5?

http://manuals.info.apple.com/en_US/iphone_user_guide.pdf

Well, you need to make sure it has been charged first.

Once you are sure it has a charge, Press the Home button (the large round button in the middle bottom).

If that doesn't turn it on, then it has been completely powered off - press on the button on the top right-hand side of the phone until the Apple appears.

Cheers,

GB