I want to add payment to my iCloud

See the following Apple articles:

Add a payment method to your Apple ID -> Add a payment method to your Apple ID – Apple Support (UK)

Payment methods you can use with your Apple ID

Payment methods you can use with your Apple ID – Apple Support (UK)

fyi: Not all credit & debit cards seem to work with App Store / iTunes Store, try a different one, or preferably a credit card. If your card is not accepted as a paymenf method, you need to contact your bank.

Add money to your Apple Account balance -> Add money to your Apple Account balance - Apple Support