Please read that article. Do what it says to create a Playlist Group. You can then name that Playlist Group "Neil Young".
You can then drag and drop your existing Neil Young playlist into it. You can then Add New Playlists inside it by right-clicking on your Playlist Group.
You won't see any option to create a "subfolder" or "tree view of sub folders" because those are not the correct terms when dealing with Playlists. If you're talking about creating actual folders on your hard drive, you don't do that in MC.
A Playlist Group is like a folder, and it contains Playlists. All this is explained in the article. Your version supports it.
Good luck...