See the Zotero forums for help with that. http://forums.zotero.org/categories/

I'm not finding much help for this question on the forum. There are too many items there to page through. I have the Zotero icon down in the right-hand corner of my Firefox browser, but nothing comes up when I click on it. What's wrong? Something is not obvious to me.

I have downloaded Zotero adn restarted Firefox. However, I do not see Zotero icons on Firefox tool bar when I access the library catalog (or any other website).

see above: you should ask that question in the Zotero forum, after looking through their documentation and searching.