[Plugin: FancyBox for WordPress] FancyBox 1.3.4

I downloaded FancyBox 1.3.4 but can’t get galleries created from elements who have the same “rel” tag to work. Instead of it reading one gallery in a slideshow, it shows all of the images within that page.

What code do I need to add to my image link page in order to have multiple galleries existing within the same page, while each grouped element is shown in a slideshow by itself?

Some example code is:

https://www.ads-software.com/extend/plugins/fancybox-for-wordpress/