Recording voice over mp3 instrumental

Hi, this is my first post on this forum.
I am currently have Audacity version 2.4.2 , running on Mac OS Big Sur.
I am able to transport an mp3 audio track onto audacity and hear it playing when I press play.
I am also able to record my voice and play back the recording.
However, I am not able to record my voice while listening to the track.
I am using my built in microphone.
I would like to be able to hear the song and record over it.
Can anybody help me figure this out?

Why not? What happens?

Ensure that “Overdub” is enabled in “Transport menu > Transport options”.