Hi TJ, excellent job on Movod Ruins, it's an awesome adventure game. :)
Dreaming uses the Sound system to play audio tracks. Select "Go>Sounds" in the Finder bar to bring up the Sound window. From there you can manage all the sounds in your game. (note that the Import button sounds promising but only works with .snd files, which as far as I know haven't been in use since OS 8. You'll probably have to settle with the Record feature)
As for how the code, the SOUND command worst almost exactly like the MOVIE command:
MOVIE 0 0 movieFileName
LOOP MOVIE
SOUND soundFileName
LOOP SOUND
The big downside of the SOUND command is that sounds greatly increase the file size of your game. If your game breaches 16 Megabytes you run the risk of corrupting the entire file, resulting in content loss. So if you're working with lots of sounds, make sure to keep a backup of your game!
Hope that helps!