Tutorial for Simplistic Firefox Addon

Anyone know of a short tutorial where I can build a simplistic Firefox addon?

I'm needing to see how to:

build the XPI file
make it have an on/off toggle menu
when on, make it login to a site, wait until done, and then scrape the main page after login. So, it would involve a form post and mouse click, and then a screen scrape.
save the screen scrape to a file on the computer

Additionally, this site I'm interacting with has AJAX to build the content on the fly. So, a view source of the HTML only shows Javascript. But after the page is loaded, if I do a select all and then view source, I get a different content than view source. So, I'm hoping the FF addon can see what the browser displays.

Solution

Robert Nyman's talk "How to write your first extension" helped me a lot. You'll find it at https://web.archive.org/web/20160728010325/http://presentation-slides.googlecode.com/files/how-to-write-your-first-extension-berlin.pdf.