Hi shairaannec,
Welcome to the Apple Community.
There are two kinds of cards in Wallet : cards, keys, tickets and passes ... includes store cards etc. (not credit / debit cards).
For bank credit/debit cards to use with Apple Pay:
you might want to try this method from Apple Support:
Add a new card on your iPhone
- In the Wallet app, tap the Add button
. - Tap Debit or Credit Card.
- Tap Continue.
- Follow the steps on the screen to add a new card. If prompted, choose your bank or card issuer from the list or find them using the search bar.
- Verify your information with your bank or card issuer. They might ask you to provide additional information or to download an app before approving your card for use with Apple Pay.
- If you have a paired Apple Watch, you have the option to also add the card to your watch.
Above comes from this complete article: Set up Apple Pay - Apple Support
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Other "How to" articles are available:
Eg:
Set up Apple Pay in Wallet on iPhone – Apple Support (AU)
Make purchases using Apple Pay - Apple Support
Manage Apple Pay cards and activity on iPhone – Apple Support (AU)
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More help, if needed:
Get support with Apple Pay:
Apple Pay - Official Apple Support
All the best :-)