Change default title bar color of active window - how?

[nomnex]

I have just installed xfce on Fedora 15.

I only want to change the color of the title bar of the active window,
from the default light blue (I use the Adwaita theme) to black
(#000000) .

Could someone show me what exact part(s) I need to edit in the in the
/usr/share/themes/Adwaita/gtk-2.0/gtk file

I don't understand:
http://wiki.xfce.org/howto/xfwm4_theme

I attach the gtk file.  If you could modify, copy and past the relevant
part in the reply, I would help.

Thanks in advance.