Go to the security verification settings screen. For information on how to get to this screen, see Changing your security settings. Check the box next to Authenticator app then select Configure. This brings up a screen with a QR code on it.

Where do I find the QR code for Authenticator?

A QR Code will be shown on the Dashboard, with instructions to download Google Authenticator application. Download and Install Google Authenticator application on your phone. Launch the Authenticator application. Click on Scan a barcode.

How do I add Authenticator app without QR code?

Open the Authenticator app, select Add account from the Customize and control icon in the upper-right, select Other account (Google, Facebook, etc.), and then select OR ENTER CODE MANUALLY. Enter an Account name (for example, Facebook) and type the Secret key from Step 1, and then select Finish.