ScreenFlow is a screen recorder that you can use to talk while showing the screen you're on. ScreenFlow can help you teach things, and actually show what you're doing so people know exactly what you're talking about.
In the screen flow tutorial I made, I explained how there is one clip for sound and one clip for the screen you're showing. Whenever you make mistake, you could just delete that part. You could make yourself sound louder when you're talking, and use the ducking tool to make any noise in the background quieter. I used annotations and text boxes to point things out. Since I didn't want the top or bottom of my ScreenFlow to show, I used the scale tool to crop it out.
ScreenFlow is a good way to teach or show people things online or any thing on your computer. ScreenFlow would be great to use in the future to show presentations or to show people how to do something.