File Managers
There are two places that you can upload a document. One is the File Manager under the Page Content section. This manager is meant to be a place to review files on your system. It also can be used to upload new files so they are available for later use with the page editor.
File Manager
The other file manager is referred to the file Browser and it is accessed within the Page Editor tool.
To access, click on the "Image" or "Link" buttons
Then "Browse Server"
Page Editor's File Browser