http://awoozruja5y3x2s3dsecryqk4bnaxezwxkn6e4mbo3fdkm6odw6brhid.onion/computers/ANON_WebBrowser.php
The optional extensions are not required for protecting your privacy, but they are useful in the overall security of your browser. Some of these extensions may not be in the default FireFox add-ons site. If they aren't on the default site just search for the terms "firefox, add-on, name of add-on" in your favourite search engine and they should show up as the first couple of links.