[MikeP]

When Hoster first runs, it creates and opens an empty Playlist named "def001.hst" in the default C:\MTU\Hoster folder. The file name appears in the Title Bar at the screen top.
You can create and save an unlimited number of Playlists on the hard drive, but only one open at a time. You can create a new Playlist for every show, or the last one open appears when Hoster runs again, especially nice if the computer or Hoster crashes as you restore your show exactly where you were before.
The Playlist Window shows the open Playlist with Singers and their Songs.
Songs normally play from top down, but you can select any song and click the Play button to stop a playing song and start playing the new one. You can click-n-drag a song to change when it plays, such as working new Singers into your Show Rotation
 

Hope that helps you figure it out.
Best way to start is just add a couple of songs to the playlist and save it as test list 01 or similar. It's easy enough to delete once you have got the hang of it.