Well the first thing that you got to check is that if the web-cam has an inbuilt mic to it
If there is no mic then you will have to attach a seperate mic/headset for voice
Also check if its USB port or normal Audio/Video output...if it had audio/video cable then you will have to attach both the cable to the correct port in the Cabinet
If it has USB output cable with inbuilt mic then try to unistall and reinstall the driver software and attach the the webcam only after installing the drivers