When you hover your mouse pointer over the image you will see the title and description of the photo appear at the top of the image window. When you hover your mouse over the lower section of the image window you will see several controls appear. Here is how you use them:
This control allows you to move to the previous image, play/pause the slide show, or move to the next image in the selected album.
This control shows a preview of the images in the album. When you hover your mouse over the thumbnail it will show you a larger thumbnail of the image. If you click on the thumbnail it will load that image in the viewer. You can use the arrows at either end to scroll to previous or next page of thumbnails in the album.
This control will toggle the album view. When you are viewing the album you can click on the album you would like to view, or click the control at the bottom of the albums to see the previous or next page of available albums.
This control will allow you to view the current album in full screen mode. When you are in full screen mode you still have all these controls at your disposal, but they will be at the bottom of the screen. Pressing ESC on your keyboard will got back to the web page.