The panoramas come in two versions, one high resolution, rich in details but larger in MB, and one low resolution, less rich in details but smaller. When you have chosen a resolution below, it will download and open in a new window. It may take a while since the files are large.

When the download is ready the cursor will change to a small ring with a dot in the middle. Please maximize the window. If you want to turn for example to the right hold the left mouse button down and drag the cursor gently to the right and the view will move to the right. The more to the edge you move the cursor the faster the panorama will turn.
You can turn in any direction, up and down as well, and also zoom in and out (ctrl,shift,+,-), but it is best to zoom when you have turned around enough.