Hi Robert - to trim the unwanted end of the song, highlight the song, and place the playhead where you want the cut made. Leave enough to include a fade-out. Then use Command+T, which will split the song. Then highlight and delete the end you don't need.
See the following link which explains audio editing:
http://www.apple.com/support/imovie/audio/
Plus, of course, the Help File.
But briefly, click on the volume level bar at the point where you want the music to have completely faded. This will produce a yellow dot and a purple square. Drag the yellow dot down to the bottom, and pull the purple square to the left as far as you want the fade to extend.
Clear as mud?!
Hope this helps
See the following link which explains audio editing:
http://www.apple.com/support/imovie/audio/
Plus, of course, the Help File.
But briefly, click on the volume level bar at the point where you want the music to have completely faded. This will produce a yellow dot and a purple square. Drag the yellow dot down to the bottom, and pull the purple square to the left as far as you want the fade to extend.
Clear as mud?!
Hope this helps