This is a question for the Android version

I have a folder called "Rock". Under "Rock", I have the folders "Beatles", "Stones", etc... I then I have songs inside each folder.

How can I create the playlist "Rock" and point to the "Rock" root folder? I then want to randomize all songs from all subfolders underneath "Rock".

That's something I can do in the PC version of Foobar2000 and I want to do the same on the Android version.