Just select your microphone in the stereo mix.
- Right click on the speaker icon in the task bar (or go to the Audio setting in Control Panel) and choose Open Volume Control.
The stereo mixer will open. - Choose Options -> Properties.
- Click on the recording selector. Make sure the microphone chekbox is marked.
- Return to the stereo mixer.
- Make sure that the microphone slider is up and not muted.
- You can also select the Advanced Controls and enable the microphone boost.