Now we'll bring the audio into Flash. Open your animation file, as usual making sure that all of the layers you aren't using are locked. You should know by now how to import any file into Flash: go to File -> Import to Library
, then select the appropriate file (in this case your looping audio clip) and import it.
If you look in your library, you'll see the name of your audio file with a little speaker icon next to it, indicating that it's an audio file. You can even play the file in the preview window, by clicking the little "play" arrow in the area above the library list.