Q: i cant use any of my mastercards, i am in georgia(country) , how can i add master card on my icloud, i want to buy storage

Try adding a payment method using the link below:

Change or remove your Apple ID payment information - Apple Support

The country where your card was issued, your billing address and the region you select when you start using the App Store and other Apple services should match.

For example, in the US App Store, you should use the US address and the card of the US bank. The same is with other countries.

The best way to solve your problem is probably to contact Apple Support directly.

https://www.apple.com/support/icloud/contact/