How do I download apps on my iPhone?

Every time I try to download FREE apps on my iPhone it tells me that I need to put in my billing information. It's only started doing this recently and I'm 16 so I don't have a credit/debit card so I don't know what to do about this.

Fjk

Even free apps require a credit card number on file (just in case you make a mistake and download a pay app so they can bill your card). After you register a cc number, you will not be billed for any free app

Go to the app store
scroll all the way down
view apple ID
enter password
go to payment information
go to where you put in the card number
select "none" for payment option
in some cases if "none" isn't an option you may need to take it to the apple store i learned the hard way but i hoped this helped