Push stop in the transport panel so that u zero the track if u are starting from the very beginning or taking it 'from the top' or if not from the beginning (hook,second verse) in ur playlist use the top bar where the cursor scrolls as the track is playing to select a starting point in the track for u to punch in from, but give urself a little extra room before u start spitting, u can always cut that empty space out with the razor tool later. Next click the floppy disk at the bottom of track 12 so that it highlights and u are now ready to record.
Open the mixer and select the track u want to record into so that its highlighted.for example track 12 then plug in some headphones and select ur interface or soundcard as ur input in the top right corner of the mixer, at this point u can talk into ur mic and u can tell that its coming in because u can hear urself in the headphones and u can see the levels for track 12 going up and down in the mixer.