Microphone

After you've plugged a microphone into a microphone jack on your computer and turned it on (if the microphone has an on button), follow these steps.

1. Open Sound by clicking the Start button Picture of the Start button, and then clicking Control Panel. In the search box, type sound, and then click Sound.

2. Click the Recording tab, click Microphone, and then click Properties.

3. Click the Levels tab and make sure the Mute button looks like this Picture of the Mute button turned off. If the button looks like this Picture of the Mute button turned on, click it to turn on sound for this connection, and then click Apply.

4. (Optional) To listen to microphone sounds through your speakers or headphones, click the Listen tab, click the Listen to this device check box, and then click OK.

Also, take a look at this site for more information!
Source: http://windows.microsoft.com/en-US/windows7/Connect-a-m...

I hope this helps!

Brett M,
Windows Outreach Team