First off, thanks for this great product! donated to offset my stupid question below (and ofc cuz i love it )

Trying to find out how to make my images work like on the demo page. (ie the last click creates a window and darkens the background)

My install:
Zenphoto version 1.4.2.4 [10045] (Official Build)
Current locale setting: nl_NL.UTF8
Current gallery theme: Default
PHP version: 5.3.10
Graphics support: PHP GD library bundled (2.0.34 compatible)

http://cacevers.nl

Thanks in advance.

You need to activate the colorbox plugin and for the default theme you need to add the colorbox define to call. See the colorbox website how to do that. There are also numerous topics on the forum.