From the OP: I have learned quite a bit since my original post. I'm using iTunes to convert my CDs to AAC format.
I like to listen to classical music, which needs to be organized by composer (rather than by song title). So after copying the iTunes files to a flash drive, I create new folders (directories) and organize them to my own liking.
So I have a Puccini folder, which contains a Tosca folder, which contains a Callas folder, which contains the folders created by iTunes. (One Itunes folder per CD. Most operas require two, three, or four CDs.)
To find what I want on my flash drive, I use the command EXPLORE DEVICE. That displays the folders (directories) at the top level. From there I can go down the chain, just like on a computer. So, if I want the Milanov version of Tosca, I go to Puccini, to Tosca, to Milanov. Then PLAY ALL.