I want to get my belly button pierced but do you need a notary from the bank?and how do you get one?

You don't need a notary from the back... I don't know where you heard that.
You need a parent's permission (and presence) if you're underage (and for that, check the laws where you reside).
If you're not underage, you can go by yourself, but you'll need to show a valid government picture ID, that has your birth date on it.