Want to share Apple store card

If it is an Apple Store card, and not an iTunes or App Store card, then it can only be used in Apple's bricks-and-mortar stores and their online store.

If it's an iTunes or App Store card then it can only be redeemed onto one account and can only be used to buy content for that account - it can't be shared between accounts. It will be available wherever you use that iTunes account e.g. on your computers and devices, and can be used in the App store, iTunes store, ibookstore and Mac App Store