Q on Sansa e280

I want to ask if anyone knew how to organize their music on the e280. I drag and drop music files into a specific artist’ folder and try to make subfolders into the artist’ folder for different albums. However, when I turn on the player and check the folder they aren’t separate albums (just one big list of both albums into one folder) and some songs just turn up as ‘Unknown’ if not put into a subfolder. Can anyone help with this problem?