Setting your computer for multi monitor output.

    Go to Start, Control Panel, Display (Personalization in Vista), Settings, select the big number 2, check the box,  "Extend the desktop to this monitor"

    This will set the computer to output to a second monitor.  If your monitor still does not display an extension of your desktop you now have to set your monitor to the be display the right input channel.  Is your receiver set to the proper line in?
    Some times you may need to restart the computer, external monitor, or both in different orders to get your hardware to detect each other but if your hardware is correct, and all the cables are the right type and in the right places it will eventually work.