You can change the background image of any template.  Download an image below, rename it to background.jpg and paste it into your C:\Program Files (x86)\yaDIS\templates\*yourcurrenttemplate*.  This will overwrite your current background image.  Before you do this, rename the template’s default background if you want to keep it.  You can use any image you want.  Just make sure the resolution of the image is 1920×1080.

Some templates include two background images, background1.jpg and background2.jpg.  The background.jpg image appears on the main menu of yaDIS, whereas the background2.jpg appears on the movie wall menu.

Clicking an image will open the slideshow.  Right-click on image and “Save image as”.