First install any authenticator app, which supports the TOTP method, on your smartphone. Use this app to take a picture of the QR code displayed here or enter the security key shown below it into the app. A one-time password will then be displayed in the app, which you must enter in the lower input field. A new password appears in the app approximately every 30 seconds. After a click on OK, the process will be confirmed in another dialog. Finally the new security key is displayed with its ID in the overview in the window Two-factor authentication.