ok, I think I understand the problem. I enter into the “child-theme” folder, the contents of the TwentyTen theme and customize it.
I would like to know if there is a way to add the entire folder “twentyten” in “child-theme” instead of what is contained in it?
Netweb thanks for the reply. The developer of the theme “mystique” says it supports bbPress 2.0. I initially installed the bbPress 2.0, but the problem is the same. (http://digitalnature.eu/themes/mystique/)