The session ID just seeds the random number generator so you get the same set of tracks for that session. To just generate a random set of tracks it can be left as is.
Hopefully the Number of tracks is self-explanatory. View playlist generates an HTML page showing you the tracks which would be chosen, and Listen to playlist generates a m3u playlist file which should load in your favourite mp3 player.
NewMusicRadio © 2004 Adrian McEwen.