Hi Rosie

I think you may want to reinstall it because it should be showing and it doesn't look like it is. There is another way to do this without volumetrics go to sky and choose fog height. I would seriously unistall Bryce 7 Pro and if Bryce 7 PLE is on there as well delete it as many people have had trouble with the two installed. The Volumetrics should be in the create Menu. As Water ground and cloud plains. if they are not there it would sound like Bryce isn't fully installed. Let me know how you get on and if you can't get it sorted I may know someone who can offer advice for that.

Good Luck

Karl