In the bottom right corner of the viewer there are five icons. These icons are for navigating the panorama. In order to look around left-click the panorama and hold down the mouse button. By moving the mouse left and right you can rotate the image and look around 360 degrees. In the panorama you will notice yellow coloured 'hotspots'.
Hotspots are gateways to other panoramas and photos.
Click on a hotspot and see what happens.