There are several different ways of adding citations to your EndNote 20 library. 

• Direct imports: You can download a single or bulk citation for an online source, such as SuperSearch, a database, or Google Scholar.
• Manual entries: You can enter bibliographic details manually. You would do this for non-scholarly resources such as newspapers or websites, or physical items such as a book.
• PDF imports: You can directly import PDFs into your EndNote library. EndNote will attempt to create a reference based on the metadata, however, this does not always work (in this case, you can manually edit the reference).