Organizing your sound effects in iMovie 3

1. In your user/Library folder, find the iMovie folder (create one if it's not already there)
2. Inside there, find the "Sound Effects" folder (create one if it's not already there)
3. Once you put NEW folders of sounds into this folder (eg: Movie Sounds, Laser Sounds, Animal Sounds, Other, etc)
   
4. They will show up as indented lists in the iMovie 3 audio menu when you restart iMovie and choose "iMovie Sound Effects."