VOR

I am new to this Sim and am trying to learn, and getting confused with VOR, and was hoping someone might be able to help by answering the following questions.

If I am flying a Cessna and I put the required VOR frequency into Nav 2, does that relate to the bottom VOR dial (and Nav 1 to the top dial), or can you use either dial?

Is it right that I dont tune with the OBS until I am airborne, (or until I hear the confirmation morse code transmission), and then I spin the dial until the needle centres. That then gives me the correct heading to turn on to?

I hope I have explained myself clearly enough

Cheers

Spartan