To use your virtual and/or physical debit cards with your iPhone, you must set up Apple Pay:
- Open the Wallet app
and tap 
at the top right corner. You may be asked to sign in with your Apple ID or, depending on your iOS, sign in to iCloud with your Apple ID. - Tap Debit or Credit Card and tap Continue.
- Position your card in front of the camera so that it appears within the frame to capture your card info, or enter the card details manually, then tap Next.
- Swan will verify your information and send you an authentication code, enter the code and tap Next.
Your Apple Pay is now all set and ready to go.
You may check out this video from the Apple Support website for full instructions.