OK, this is very cool. While some will argue that this is over simplified, I think it is a good start regardless.

This tutorial has been created for individuals wanting to develop full-featured extensions for the Mozilla Firefox browser. The tutorial has been constructed as a step-by-step guide providing many examples, explanations, and external references to help the reader have a full understanding of extension development.

Please use the menu on the left to navigate through this tutorial. Each section has been dedicated to a certain stage of the development process. It is recommended that you read through the tutorial in order, as some information builds upon previous sections.

The following major topics are covered in this tutorial…. Source: rietta.com