1. Look for the icon Zotero produces at the top of your page, next to the URL. If you're looking at a book record, the icon will look like a blue book . If you're looking at a journal article, the icon will look like a sheet of paper , etc. Hover over the icon to make sure it is a Zotero icon and not some other Firefox thing. Click it to add items to Zotero. If the icon looks like a folder , Zotero is detecting multiple items on the page, and it will ask you which ones you want to add.
2. If you have an ISBN for a book, or one of a few other standard numbers, you can look up a record for that book or article using the wand button in Zotero.
3. If you are on a web page that does not produce a Zotero icon next to the URL, you can still produce a Zotero record from that page, though you will probably have to fill in some of the information (author, date, etc.) yourself. Zotero will automatically save a copy of the page. To do this, open Zotero while you are on the page, and click the "Create New Item From Current Page" button, toward the top middle of the Zotero window.
4. If you have a PDF of an article already stored in a file on your computer, set up your screen so that your Zotero library is open, but you can see your stored PDF on your computer, too. Drag the PDF files to the middle window of your Zotero library (the one with the list of items), and drop it there. Right-click on the PDF and select Retrieve Metadata for PDF. Zotero will search Google Scholar for the citation information for your article and create a parent entry in your Zotero library for it. If Zotero cannot get metadata, you'll have to use another method to get the citation information, and then just associate the PDF with the citation.
5. If you are desparate, you can create a Zotero record from scratch. This option is used most often for unpulished items, or unusual formats. To this, use the New Item button .
For more on adding items to Zotero, see http://www.zotero.org/support/getting_stuff_into_your_library
Want to add items from Google Scholar to Zotero?
Change one setting and "Import into EndNote" will be added to each item in Google Scholar. Visit Scholar Preferences and in the Bibliography Manager section select Show links to export citations into and choose EndNote from the drop-down menu. Click Save Preferences and you're done. Next time you search on Google Scholar, you'll see EndNote as an option. If you are using Firefox with Zotero intalled, Zotero will grab any citations sent to Endnote.
If enough people ask for a site translator, Zotero will eventually create one.