Twine is a popular tool with robust online documentation. For more information about using Twine, including its more advanced and customizable features, check out:
Twine Website
The homepage providing access to Twine online, Twine download options, the Discussion Board, Chat, Cookbook, and Wiki. It also provides examples of published Twine stories available online.
The Twine Cookbook
A quick reference guide proving examples and code for common questions and editing needs. Maintained by Twine.
The Twine Wiki
A robust wiki page with tutorials and reference documentation for Twine. Maintained by Twine.