To use Apple Wallet to pay, first add your credit or debit card to the Wallet app on your iPhone. Open the Wallet app, tap the plus (+) symbol, then add your card by scanning it or entering details manually. After your card is verified by your bank, it will be ready to use for payments. To pay in stores, look for contactless payment symbols or the Apple Pay logo. On an iPhone with Face ID, double-click the side button and authenticate with Face ID or your passcode. On an iPhone with Touch ID, double-click the Home button and authenticate with your fingerprint or passcode. Hold the top of your iPhone near the payment terminal until you see a checkmark or "Done" on the screen. Apple Pay can also be used for online or in-app purchases by selecting Apple Pay as the payment method and confirming the purchase with Face ID, Touch ID, or passcode. You can manage cards, set a default card, and view recent transactions in the Wallet app as well.