Not all panoramas have the panotag function active.
Hover the panotag icon in the upper right corner to see if its available and, if it is, click it to show the panotag toolbar.
in this bar you can read the help page and the terms and privacy conditions
After you successful login into facebook and give access to some important info you can click in the “target” icon and then click on you in the panorama. You’re tagged.
In the next login you can use the magnifying glass to find you in the photo.