To use home sharing you don't need a credit card. Just turn on sharing in iTunes, to purchase apps your will need to have a credit card, here is a link to step-up an iTunes account without a credit card. http://support.apple.com/kb/HT2534
THanks for answering me however I do have one more! So if we want to purchase music or apps then we must use a credit card?? Is there an option for iTunes cards to purchase what we want as oppose to a credit card constantly on file?