How do I use an external monitor to work with my laptop?

From the control panel, or from right clicking on the desktop, go to your Display Properties box, and make sure that your second monitor is active(which I'm assuming it is since you said you were getting picture) After that, on your Keyboard, one of the function buttons(usually in blue) would have a picture of two monitors. I really want to say that it is f5, but I cant be certain my laptop is elsewhere right now. Once you find the button just press the function key and the monitor button and the screens should switch off for a moment and then alternate between both on same screen, one as primary screen other as secondary, and the first monitor off and your external monitor displaying the main desktop. Which is what I think you are asking about. Hope I just saved you $15

Plug in your monitor. You should have a function key on the keyboard (Fn). Press that and F5 at the same time. A little option menu should pop up. Keep holding the Fn key and hit F5 again to select between options. You want to choose CRT to display the picture on the other monitor and not on your laptop's monitor. If you select CRT and LCD, then you will have the same screen on both monitors. I hope this helps!