Check this outhttp://www.ehow.com/video_4985945_ho...l-monitor.html
And I also found thiis:
Well, you'll have some cable connections and clicking to do. First thing you need to do is plug in the power cord for your monitor and connect your monitor to your laptop via a cable. Hopefullly your laptop has a VGA connection on the back that your monitor can hook into (a DVI connection would be even better, but only newer laptops would have that). There'll only be one type of connection that the cable can connect to. Once your monitor is connected, you'll want to make sure it works. Go into either your desktop settings or your video card settings and you'll want to "extend windows desktop to this monitor" for the attached monitor. Right click on desktop, go to properties. Click Settings tab, then click the Advanced button. There should be a tab for your video card, everyone has a different one so I can't explain exactly how yours looks. Go to that tab and search for something like "clone" or "extend desktop" to the second monitor. You'll want to select that, then click Apply/OK until you see your desktop extended to your other monitor.
Then you'll want to change some settings so your laptop continues to stay on when you shut your laptop. On my laptop (its pretty old) there's no way to get the VGA output to stay on when the laptop is closed. The laptop will stay on, but the VGA output quits. Yours may be different and may work. Others may have advice too. To change these settings, go to Start --> Control Panel --> Power Options and click on the Advanced tab. There should be some drop down menus asking what you want to do when you close the lid on your laptop. Choose "Do Nothing" if you don't want it to turn off. Click Apply/OK and you're set.