Does anyone know of a tutorial or a demo that explains the different settings for creating fog in a scene?

I can create a pretty basic fog, but I'd like to create rolling fog for a scene that features cloudy steam. I could probably use some 2D planes but then I wouldn't learn more about Carrara, would I? ;)
Thanks in advance!

P.S. -
I really like the forum here. I feel like I can ask questions and I get real feedback and meaty info. Thanks so much!