It's easy to make Harry display your own digital pictures! First, find the pictures you want him to display. They can be either jpg, gif or png files.
Put all the pictures you want him to display in a folder. Then go to the screen saver settings (see below) and make sure the "Display Pictures" box is checked. Then click the button labeled "Folder Containing Pictures To Display" and select the folder where you put all your pictures and click Open. Then click Save and enjoy seeing your pictures displayed in magical 3D! Easy as that.
Just a few tips tho. If you have really high resolution images, there will be a pause as the image is loaded which can interrupt the flow of the screen saver. It doesn't do anything, but it's not so nice to watch. To remove the pause, use images that are a lower resolution, or resize your images down a bit. But it's not entirely necessary to do it, just if you get a pause. Other than that, just enjoy it!