Open your iMovie project and click on the Audio button below the clips
Insert your audio CD into the computer. (The eject button is the up
arrow on the top right of the keyboard.)
The drop-down menu above the audio pane may default to "iTunes
Library." Select from this drop-down menu the title of the CD you've
inserted. You should then see the tracks listed in the audio pane below
the drop-down menu.
To the far left of the play button are two box-shaped buttons, one
with an icon of a film strip for adding and arranging video clips in the
clip viewer, and the other with an icon of a clock for adjusting audio
and video timing in the timeline viewer. Select the clock for the timeline
viewer. Now you can see the three audio tracks, the top being the audio
embedded in the video and the other two for adding audio tracks.
To extract the audio embedded in the imported video (represented on
the top layer of the three audio layers in the timeline), select the
clip you wish to extract from, and select "Extract audio"
from the edit menu along the top. When it's finished extracting, you
should see the extracted audio track below the clip in the second layer
of the timeline.
To adjust the volume of a track, click the "Edit volume" checkbox
at the bottom. You will now see a vertical line drawn through the audio
clips on the timeline. This represents the volume level. You can adjust
the entire volume level of a clip by selecting it and sliding the volume
fader at the bottom. If you wish to make volume adjustments within a
clip, click on the clip at the point you wish to adjust. This will create
an in and out point for the volume, each of which you can bring up or
down by dragging it with the mouse.
To import a track from the CD you've inserted, select the track you
wish to add from the audio pane. Place the cursor, or playhead, at the
spot in the movie where you want to add audio, and click on the "Place
at Playhead" button beneath the audio pane. Wait while the track
imports and is placed beneath the clips in the timeline viewer.
To crop the audio clip, adjust the start and end points by dragging
the triangles at the beginning and end of the clip and selecting "Crop"
from the edit menu, just as you would a video clip.