On the 'Connect your microphone' panel you will see an icon for each of the microphones you have attached to your computer, click on the microphone you want to use, mouse over the icons to see the full name of the microphone.
If after you've spoken in your normal voice and still have the "We're not detecting any sound from this microphone. Please speak up, or select another microphone" error message it may be that your microphone gain needs adjusting.
Adjusting your microphone
1. Click on the 'Apple Icon' in the top left-hand corner of your screen. Then select 'System Preferences' > 'Sound' > 'Input'.
2. Select the input device whose volume you want to control.
3. The input level meter shows you how loud or soft the sound from the selected input device is registering.
4. Drag the 'Input volume' slider left or right to lower or raise the input volume.
5. If the sound input is very quiet, raise the input volume. If the input is very loud, lower the input volume, so that your recording isn’t too loud or distorted.
6. To capture less background noise when using your computer’s built-in microphone, select the 'Use ambient noise reduction' checkbox.