There are a number of ways to get books, articles, web pages, video clips, blog posts, and other kinds of information into Zotero.
Zotero allows you to save references from most library catalogs and database, and even some regular web sites and online videos. If Zotero detects that your looking at a book or an article on a catalog, database, or website, you will see a book or page icon appear beside the address bar of your browser. Just click the icon and Zotero will automatically save the citation. If you use Zotero Standalone you will need to make sure you have the program open before you start saving citations. Zotero will save to the folder you have open, so make sure you have the correct folder open before you start saving!
On a page of search results you will notice a folder icon in place of the book or page icon. If you wish to save multiple items in a search you can click the folder icon and then select the books/articles of interest in the pop-up and click "OK". If you are in a database with multiple pages of results clicking on the folder icon will only show you that page of results.
Zotero includes a feature that allows you to retrieve the citation information, or metadata, from many article PDFs. Simply drag and drop your PDF into the middle pane of Zotero. If Zotero can detect the citation information, or metadata, it will automatically create an item in your Zotero library for the article.
The ability to retrieve PDF metadata will not work with every article PDF. If trying to retrieve PDF metadata in Zotero does not work you can manually add the items.
Manually inputing citations is a good option if you have a PDF that you cannot retrieve the metadata from, or if you want to add a citation from print source. To manually add citations click the green plus sign above the middle column and select your document type. Once you have selected the document type fill in the Title, Author, and fields related to publication/publisher information.