Desktop files have disappeared from my Mac desktop, yet again - but visible in my Mac backup folder

This has happened to me many times, and each time I fixed it by laboriously looking for missing files on my Mac and restoring them from an attached backup drive.  However, I don't have access to that drive at the moment.  Fortunately, the files can be seen by navigating to the backups folder in the Dropbox web page.   

I saw some other postings about the backup no longer mirroring the files but rather copying them to a backup folder.  This is fine with me - the old organization was confusing.   

But, how do I restore from the Dropbox BackUp folders to my empty Mac folders?  If I navigate to the "Mac" folder under the dropbox in my Finder, the desktop folder is empty (well, it contains a test file I just made but all the former desktop files are gone.)