Dubbing music over narration into separate tracks

I’m trying to add music to a poem narration. I would like the music, recorded after the narration, to be in a separate, synchronized track so that I can manipulate it separately.

What’s happening is that if I don’t mute the narration track, the next track has both music and narration together.

How do I lay in a second, separate track while hearing the first track so that I can play in response to it?

Using Windows, feeding through a Tascam mixer.

Thanks!