Hello,
If I undersood well, you want to change the background color. If your are working in 3D (assembly, modeler...) then you can have a new menu with clicking CTRL+M. Then options and background color.
If you are working in 2D (masterdrafting) then you go to the top right, click OPTIONS (if you don't have this option menu, click PF) then interface and background color.
Regards