Click the round green button at the top of your Zotero pane. (If you hover over it, it will say "New Item") Select the type of item you want to enter (e.g., Journal Article) from the dropdown menu, and then enter the citation information in the appropriate fields in the right column Your reference will automatically save!
Zotero provides the ability to save references from most library catalogs (including ODU's) and databases, and even some regular web pages, with one click. (Zotero publishes a list of compatible sites, and many sites not on this list also work.) If Zotero detects that you're looking at a book or article on a catalog, database, or a site like Amazon.com, LibraryThing or the New York Times, you'll see a book or page icon appear in the address bar of your browser. Just click the icon and Zotero will automatically save the citation.
If you're on a page of search results with many items, you'll see a folder icon instead. Click this to get a list of all the items on the page, and check off the ones you want to save.
Click the round green button at the top of your Zotero pane. (If you hover over it, it will say "New Item") Select "Link to File" from the dropdown menu. Choose the PDF you want to upload. Optionally, right-click the PDF and select "Retrieve Metadata for PDF" --> Zotero will then try to create a complete citation from the PDF information.