How do I add a credit card to my iPhone's wallet and purchase using Apple Pay?

 How to add a credit card to your Apple Wallet:

1. Open the Apple Wallet app
2. Tap the + sign on the top right-hand side of the screen
3. Select card type and continue
4. Input card information
5. Follow remaining instructions (this may vary due to previous selections)

How to use Apple Pay:

1. Unlock your iPhone
2. Quickly double-tap the power off button on the edge of your phone (an image of your card will be displayed on the phone screen)
3. Hold your phone over the payment terminal. A sound will indicate a successful purchase.