You can think of the Office Files panel as a database 'ftp' site. Files can be dragged into the panel from the Finder in order to save them in a central location accessible to all of the users on the database.
Press the Patient Billing item in the toolbar to see this view:

Pressing the toolbar item will reveal the Office Files panel:

The panel uses the familiar Finder browser layout. You can create new folders by pressing the 'New Folder' button and rename them using the 'Rename' button.
To populate a folder, just drag and drop files from the Finder.
To use a file found in the panel, just double-click on the file icon. Doing so will allow you to work on a copy of the file, rather than the original file. You will be prompted for a name to give the new copy before you can begin working on it.