To begin, make sure the merchant you would like to purchase from accepts Apple Pay. If they can accept your Apple Pay payment, they will have one or both of the following icons on their terminal:
If you would like to pay with an iPhone with Touch ID, just place your finger on Touch ID and hold the top of your iPhone near the contactless reader until you see Done
and a checkmark on the display.
If you would like to pay with Apple Watch, double-click the side button and hold the display of your Apple Watch near the contactless reader. Wait until you feel a gentle tap. A subtle vibration and beep will let you know your purchase was successful.
If you are paying online or in App, simply tap the Apple Pay button and follow the on-screen prompts to complete the transaction.