Hi Agnes,
Welcome. We are all Apple users, like yourself, in this community.
Seems you have to be thirteen (birth date listed in your Apple ID account) to use Apple Pay.
Younger children can use "Ask to buy" if you have "Family Sharing".
(meaning the parent ok's each purchase made on the card the parent lists.)
Discussion thread:
What age do I need to be to use Apple Pay… - Apple Community
___________________________________________________________
Re: Can anyone provide me with a list please?
The available lists of countries do not come with the age requirement listed.
Countries and regions that support Apple Pay - Apple Support
Cards that can be added would need to be from card-issuers who participate in Apple Pay:
Apple Pay participating banks in Africa, Europe and the Middle East – Apple Support
Here's a link to the Apple Pay Support Website.
If needed: There is a "Get Support" link at the bottom of the page that opens from the link.
Apple Pay - Official Apple Support
or
Apple phone numbers around the world
Contact Apple for support and service - Apple Support
All the best :-)