At any time you can navigate to other documents, folders, and folders sets with your “Files” application. In the white bar at the top of your screen, you will see the name of the folder you are in. You can click on this name of your folder in the bar at any time to navigate up or down through your folders and files. For example, in the image below you are viewing a single document and how you can drill up all the way to the folder set level.
You can also navigate between other Documents in the same folder by using the “<<” and “>>” buttons that are at the top of your Document when you are viewing it. See the image below: