How do you fly up and down in might and magic 6? I cannot find the equivalent keys on my mac keyboard.

Well, on my PC keyboard, it's the group of keys Insert, Home, PgUp etc. I don't remember which is which, but two of those are for flying up and down, and one disables flying (don't use it in mid-air). Check that you have levitation active, and that you're not in an indoor location. You can't levitate indoors.