Can't use App Store gift card

Hi Amin_2004sonoio,

Welcome to the Apple Community.

Wondering which Apple Gift card you have, and where you tried to use it.

If you can't redeem your Apple Gift Card or App Store & iTunes Gift Card:

https://support.apple.com/en-us/HT201195

Your Apple ID is the account to use for adding a payment method to use for everything Apple.

including iTunes, App Store, iCloud etc.

How to create your Apple ID if you do not have one::

https://support.apple.com/en-au/HT204316/

Check the payment methods that you can use with your Apple ID:

(Scroll to choose your country,)

https://support.apple.com/en-us/HT202631

Change, Add or Remove Apple ID Payment methods

https://support.apple.com/en-us/HT201266

Hope this helps you use your gift card.