Don't bother being on this thread if you are just gonna troll. Can you put a debit card onto an iPod touch 4th gen? If you can then how?
I don't think so... Debit cards use magnetic strips.. Imitating a magnetic strip to create an identical card is what I think to be illegal.. Not sure though..
If you mean in iTunes or the AppStore, it should be the same way as you normally would put any payment on your account.