How to Toggle Monitors
Whether using a desktop or laptop computer, most video cards give you the option to view your PC on more than one monitor. If you connect a second monitor to your main PC, you can go into the Windows display settings or use keyboard shortcuts to toggle between display options. For instance, if you have a laptop and want to connect it to a home monitor with a larger viewing size, you have the option to toggle the monitor screen off and turn the external monitor on, or you can use both simultaneously.
Connect the secondary monitor to your computer through a video port such as a VGA or S-video connection.
Click "Start," then "Control Panel," then click the link labeled "Adjust screen resolution" under the "Appearance and Personalization" section.
Click "Detect" to have Windows search for any monitors that have been connected. You can skip this step if you see both monitors listed at the top of the display screen.
Click the drop-down menu beside the "Display" option, and select the monitor you wish to use from the list.
Click the "Multiple Display" drop-down menu, and choose "Show Desktop only on X" (X represent either 1 or 2, depending on which monitor you wish to toggle on).
Click "Apply Settings" and then click "Keep Changes" to save the monitor settings. You can go back and repeat this process to toggle between monitors 1 or 2.