We are fellow users here on these forums, you're not talking to iTunes Support.
Are you getting an error message ?
The iTunes gift card field is optional, you don't have to fill it in. Also iTunes gift cards aren't available in all countries, and they are country-specific (they can only be used in their country of issue), so you may not be able to fill it in anyway. If they are available in your country then you might be able to buy them from Apple, or from electrical stores, supermarkets etc