Do I need this feature?
This is at the top of the section as unless you fancy trying your hand at making Tinderbox-based Tinderbox demos then you can skip reading and move on.
To use this feature you'll need a plain text editor (such as TextEdit in plain text mode) or better TextEdit Plus, TextWrangler, BBEdit or the like. You'll also need some knowledge of XML syntax rules (there are plenty of web demos).
What does it do?
The Tinderbox XML Tutorial syntax lets you use simple XML files to set up tutorials and demos of Tinderbox effectively by internally scripting the application. An example is the basic tutorial that ships with Tinderbox (The built-in tutorial lives in the Tinderbox.app:Contents:MacOS:tutorials sub-folder of the Tinderbox application package - Cmd-click the app in Finder and select "Show Package contents").
Can I demo all aspects of Tinderbox?
No - you can't show things like dialogs. Indeed, the Tutorial syntax is aimed primarily at demonstrating the Map view mode of Tinderbox. If you can get your concept across in Map view then a Tutorial is probably worth trying.
Are there examples to copy from?
Yes - locate the basic tutorials shipped in Tinderbox (the folder location is cited above) and open any of the '.tut' files in a text editor - preferably something like BBEdit that can colour the syntax for you.