Zotero provides the ability to save references from most library catalogs (including ISU'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, 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.
It's easy to add PDF's you already have on your computer. Just drag the file into the folder/collection. Dropping a file onto a collection, or in between library items, will copy it into your library as a standalone item. Then, right-click on the PDF and select, 'Retrieve Metadata for PDF'. You will only see this option if you have installed the PDF indexer. You can do this by selecting the Zotero gear icon, going to Preferences and selecting 'Install PDF Indexer'.
Each item also has an Attachments tab in the right column. You can attach files by clicking the Attachments tab and then the Add button.
Click the Zotero button at the bottom of your browser to open your library. At the top left is a folder button with a green plus sign. Click this to create a new "collection."
Create collections to organize your references. Collections are like file folders on your computer, but a reference can be in more than one collection at a time. In other words, a book on the Civil War could be filed in your "Civil War" collection, your "Georgia History" collection and your "19th Century America" collection without having to make three copies of the reference.