I put 15 on it and wanna download a movie but it won't allow me to download anything it say payment information required i put my password in then it asks for a debit card and won't except my iTunes money
Could be many reasons but your not giving enough information, from what you just said you are probably not redeeming your itunes card, it sounds like you are putting you itunes card number in the debit/credit spot and you cant do that. Google "how to redeem itunes card"