Yosemite multiple desktop screens
I've been in Yosemite for while and just now noticed that you can have more than one desktop area, just to make sure I'm clear here this is what I mean.
My regular desktop will show with lets say mail and my downloads open, then if I mouse to the side I get another desktop with other windows open. Can someone let me know how to either make one desktop or how this feature works?
Thx
RD
iPhone 5, iOS 8.1.1