how can I add payment to fund?

Add money to your Apple Account balance

1. Open the App Store app.
2. Tap your photo, initials, or the sign-in button at the top of the screen.
3. Tap "Add Money to Account."
4. To add funds instantly, tap the amount that you want to add. ...
5. Follow the onscreen instructions to complete the purchase.

Add money to your Apple Account balance