How do i open Apple Pay

Start here→Set up Apple Pay - Apple Support

First you need to add a card to your Wallet, then you can double click the side button to bring up your default card to use at a retail location that accepts Apple Pay. Also if you hold the iPhone up to the terminal it will open the Wallet up automatically so you can complete the purchase by double clicking the side button.

Review the Related Article on the top of this page to set up Apple Pay and add a card.