Go to the vendor’s website of your webcam to download the Windows 8 drivers to make the webcam work with your Windows 8 operating system. If the drivers are not available, it means that Windows 8 supported drivers are not so far released by the manufacturer. Wait for some time until the drivers for Windows 8 are released. For the time being, you can download Windows 7 drives instead and try to install on Windows 8.
Ensure that you had your backup of important data before installing the Windows 7 drivers as they may or may not work with Windows 8. So keep your things safe.
Hope this helps.