Open skype go to tools from the drop down list select options scroll to audio settings
you can make a free test call before you try to make a call
make sure the microphone is using the same as your computers audio
you can make a free test call if you cant get the microphone to work you can select learn about setting up your audio equipment also
click start control panel sounds and audio devices audio and also voice it's the same make sure that you have the right default microphone selected you should be able scroll to video settings to make sure you have the right settings
Open skype go to tools options scroll to audio settings or video settings you can see the webcam there you can even take a snapsot also make sure your settings are correct for a video call