Hi Tysyacha- I use Final C

Hi Tysyacha-
I use Final Cut, but most editing software is similar: in the Timeline, there should be an audio and a video section. In the audio section you want to create at least 2 tracks (one for the music, one for the narration). This way they both play.

It’s hard to advise you about the mike issue from here.

Hope that little bit helps.

Paul