Windows 7/8 is supposed to provide the webcam drivers for most Dell computers. If you system needs webcam drivers, go to Drivers and Downloads enter your service tag, then select your operating system. If your system needs webcam drivers, they'll be listed under Input.
(Windows 8)How to make the webcam work with help from this youtube. You have to open the Camera app first, and then click Settings on the charm bar to see where you can give the app permission to use the webcam.