In AVID open the Audio Punch-In tool

Go to >Tool>Audio Punch-In

The important things to choose are the Input source which should be

Built in Microphone if you are on a laptop or IMac


Also choose the storage drive and Bin to put the recorded clip into

Mark and In and Out point on your timeline that delineates where the Narration will be placed in the timeline on the newly created audio tracks.

Mute the audio volume on the computer 



Click The Record button to start recording.

Recite the narration that you want to record.

Press the stop button or space bar to stop recording.

When you finish recording the audio will be placed on

new tracks on your timeline like this example

Edit just like any other master clip.