Learn more about hyperlinks.
For most day to day purposes, a hyperlink to the document you are citing will be sufficient. A hyperlink basically says, I am referencing this item and you can follow this link to another document to learn more.
One of the problems you may encounter with hyperlinks is that you have no control over the external resource. The page could move, or get deleted, or some other circumstance that now makes your content less effective.
There are now hosted services out there that let you archive a reference indefinitely. Websites like archive.today exist to create permanent snapshots of a live webpage, with all the graphics and text. And then you can link to the resulting “archived” URL to make sure the resource you referenced is always available to your readers.