I just published an article on how to use NVDA and Firefox to do website testing.
This article can be found on the front page of my blog under the “Pages” section, in the “Articles” sublist.
The article is meant as an introduction, not as a replacement for the NVDA user guide, and it is certainly not meant to replace other accessibility testing tools you might use for your website testing, just as an additional tool to help you get a feel for how blind users interact with your web sites or web applications.
I plan to update the article periodically as new versions of NVDA become available, features are added and other info relevant to the article might change.
Enjoy the read, and feel free to leave feedback!