Audio mixdown and add audio track

I don't know Cubase, but here is a Sonar method. Doing this in Track View.
Freeze the midi track; this will make an audio. Next,
Select 'Shift-Ctrl' on your keyboard and drag copy the freeze track to a new track. By holding the 'Shift-Ctrl' keys and dragging down to the open bottom of Track View will automatically create a new track. Next,
Do the same with the audio track; But drag copy the audio track onto the newly created audio track. Doing this will combine the two tracks.