Here's an example of a puzzle activity built from scratch.

1 : create a folder

Create a folder called "my_activities" as a subfolder of omnitux/data ("C:\Program Files\omnitux\data on Windows")

2 : add multimedia elements

Save a single image called "my_picture.jpg" in the folder "my_activities" created during step 1.

3 : setup the puzzle activity

Download (right click - "save link as") this example XML file with comments in your "my_activities" folder.
You can check/modify its contents with a text editor (basic editors like wordpad are ok, but it is better to use an editor doing XML syntax highlighting)

4 : try the puzzle !

Run omnitux
Make sure you select the English language.

Your new activity should automatically appear in the puzzles menu.

If something does not work, check the file omnitux/log/omnitux.log

More customization

The easiest way to build new activities is to copy and then modify some existing XML files from the "omnitux/data" folder.