The slide shows are a bit touchy so here are some pointers.

There is a giant arrow in the middle of the slide show when it is not running. You would think that would start the slide show but it usually leads to the location of the material which is on Picasaweb or Google+. No problem there, you can view full page slide shows or view the photos full page which is nice and something that is restricted in the methods that I use to connect the content to the site. To start a slide show, click somewhere on the black border around the first photo in the slide show, that will start the presentation.