A. ) Configure audio line for microphone recording
In order to record from microphone, you should have a microphone connected to your sound card and you need to enable recording line for microphone. Just click the button for Audio line configuration , then the Audio line configuration window will be opened: Click on the microphone ( "Mic" as shown in the left picture, the name may be different in your computer ) socket to select the audio line for microphone recording.

Note: After changing the audio line to microphone recording, if you want to record played back sound again, you need to set the audio line back to the played back sound recording. If you want do that automatically , just click on the green button.
B. ) Click the red button to close this window.
C. ) Click the record button to start recording.