how can i download anything as it wont accept my card

Welcome to the Apple Support Communities!
I understand you are not able to download anything from the iTunes Store because your payment method is not being accepted. The resource below provides some information about the various forms of payment that are accepted. If you don't want to use a bank card, you could purchase a retail gift card to put a balance on your account.
Payment methods that you can use with your Apple ID
Change or remove your Apple ID payment information​
Take care.