What you are trying to achieve IS possible, but you will have to buy some extra equipment:
You will need a wireless receiver to receive the video signal transmitted from the existing wireless camera.
The monitor that came with the camera probably has the receiver built in.
If it has a connection for an external monitor then that is the easiest way to go, but I suspect it hasn't, so you will need a different receiver to feed the video signal to your laptop.
There are plenty of these on E-Bay at around £20 - £25 - search for "Wireless CCTV" - they are adjustable within the 2.4GHz frequency band so should work with the exisitng wireless camera, and can be powered by a 12 volt external supply.
You then need to get the video into your laptop, and it is unlikely you will have a built in video capture card, so you will also need to purchase another device - search E-Bay / Google etc. for USB Video Capture.
You should then be able to capture the video from the new receiver directly into your laptop.
HOWEVER - If you're going to use yur laptop why not just call it quits with your existing kit ( maybe re-sell it on E-Bay ) and just get a USB web cam ? - Plenty of choice, plenty of different features available, and will probably cost a lot less :-)