How do you look on the back of a Card in my Apple Wallet.

After setting up my AMEX to my iWatch I received an Email from Amex. - below is from that eMail. - it seems to tell me to look on the back of the Card within the Wallet application to find the Device Account Number and use the last four digits if the merchant asks for my card number. How do you turn a card over in the App?

A Device Account Number has been created for your Card on this device. This number is separate and unique to your watch and different from your plastic Card number. If a merchant asks for your Card number after you've made a purchase with your Card in Apple Pay, please use the last 4 digits of the Device Account Number, which you can find by viewing the back of your Card in the Wallet app or in the Wallet section of the Apple Watch app, if using your Watch.