Apple Logic Pro /LogicExpress Discussion

I'm learning so much from the macProVideo tutorials - thank you for  
recommending them. I'm on mastering at the moment and the tutorials  
use a single stereo track. This is probably a stupid question, but do  
I first bounce the various tracks in my song before mastering?

I'm sure that's what I should do, its just that I haven't actually  
been told to do that so maybe there is another way of doing it.

thanks in advance

Andy B