CD
Cameron David
Clarity Expert
Modern Operating Systems have built-in support for screen recording.
Windows: http://winsupersite.com/windows-10/how-use-windows-10s-screen-recording-utility
Mac: https://support.apple.com/en-us/HT201066
There are also more powerful standalone applications like Camtasia that are popular, but all allow you to record your screen and an audio source like your computer's microphone.
Hope this helps.