On a computer:
To setup Google Authenticator while using a computer or tablet, open Authenticator, press the Plus icon on the bottom right of the Authenticator app. Then scan the QR code with your phone, setting up a new entry in Google Authenticator. Scroll to the bottom of your Google Authenticator, tap the new entry for this site, and copy the number into the field presented to you. This will confirm that you have set up Google Authenticator successfully.
On a mobile device:
If you are setting up Google Authenticator while using your mobile device, use the Setup Key below the QR code to create the Authenticator entry. Then scroll to the bottom of your Google Authenticator, tap the new entry for this site, and copy the number into the field presented to you. This will confirm that you have set up Google Authenticator successfully.