Right-click on your desktop.
Select Properties
Select the Settings tab
Click the Advanced button
Now as for the next step, that is different for different computers. It depends on what graphics card you have installed, whether or not you have installed the proper drivers for it (or if you are running the default generic Windows driver) and also what version of those drivers.
But basically at this point there should be an option in there for color management, gamma, display, or similar options that affect the display.
~Ray B.