Here's an easy tutorial for Flash beginners on how to add sound loops to the flash movie.
1. First off, open the Flash file. Then click File>Import and select the music file you want to insert. Alright, now click Insert>New Symbol. Call it "Music File" and behavior as a Movie Clip. (Click on the image on the left to expand.)

2. Once inside, click on the first frame on the timeline, then go to the Sound Tab and select the sound file from the drop down menu and change the loop to 99999999. This will make sure it keeps playing for a long time :) Thats it folks. Not to hard was it?

3. Now go back to the main movie scene and go to Window>Library. Drag and drop the "Music File" icon anywhere on the movie screen. Voila, finished, not too hard was it?
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