To install a second monitor on a computer:
Plug the second monitor into an open DVI port and restart the computer. If the computer doesn't have a DVI port, connect with a DVI-to-VGA adapter.
Once Windows starts, right-click on the desktop and select Properties. Select Display Properties, and then click the Settings tab.
Click on Display, and then click on External Monitor. Select Extend my Windows Desktop onto this Monitor, and then select Identify.
Drag the monitor icons to match them on the screen, and then select OK.