To get the audio and video to play together drag a Slug effect into the Timeline from the Video Generators folder in the Effects tab of the Browser and edit it into the Timeline wherever there is a gap in video.
Upgrade to
Final Cut Express 2.0.3 or later to avoid the need to use a Slug.
Note: A Slug is a video clip of a black image with an empty pair of audio tracks. Use it as a placeholder in areas where you want to keep a gap between two clips.