The photo gallery is broken down into various ablums. 

Once you have selected an ablum, a slideshow of the images in the ablum begins.  If you move your mouse near the top of the image a slideshow control bar is displayed that allows you to pause/play, go back, or go forward within the ablum. 

If you click on the image it will shrink and slide to the left.  In many cases, a commentary is provided to the right of the image.  You may select the link under the commentary to view the full sized photo.