What add-on have you installed? Have you checked to see if the author of the add-on has any support options of help pages for the add-on?

You can try the procedure in the how to customize the toolbar article to see if you can add the icon for the add-on to the toolbar.

"ScreenGrab"

OK Im confused....Im a died in the wool IE user...new to firefox....not impressed yet...if firefox dosent automatically add a button for toolbar add ons how in the world does one access them?

I don't get it....what am I missing?

You can read this article:

http://groups.google.com/group/screengrab/browse_thread/thread/f3529f8002201a16/b8add27f691c1bd8?lnk=gst&q=icon+in+firefox+#b8add27f691c1bd8

https://addons.mozilla.org/en-US/firefox/addon/1146/
Under the Website category on that page.
http://www.screengrab.org/
" To use it, just right-click a page to bring up the context menu and look at the options under “Screengrab”. It’s pretty self-explanatory! (if you don’t see the menu then something must be broken – better send me an email). "