trimming the middle of an audio clip

One way to do it:
Drag it in twice and drop it on the frame where you want it to start.. Trim from the back of the first one. Trim from the back of the second one.

Hi deb - in imovie 6 we would simply split the audio clip then drag the new ends to remove the middle part. I do not use 09, but the following link may help you to do that in 09:
http://www.unlockingimovie.com/2009/02/quick-tip-split-clip-at-playhead.html

Another way to do it:
This works best if your video clips have a voice track that you want to use while the song is muted in the middle.
Select the frames in the Video clip where you want the song to be silent. There should be a yellow border around these clips. Then right click inside the yellow border and select Split Clip. Open the Inspector for this newly split clip, and go to the audio tab. Turn on the ducking feature and set ducking to reduce the volume of the other tracks to 0% of the voice track.

For more on how audio works, see [this Video Tutorial|http://www.apple.com/findouthow/movies/imovie08.html#audioclips]