Musescore Tutorial

You can use programs such as Screenflick to capture everything on your screen as well as sounds from the computer and or mic. Be aware that Musescore you must cahnge the I/O (inoput/output) source from the main menue -> Preferences -> I/O, and that you must Quit Musescore and then resart it for the changes to take effect.

The type of video tutorial you've described is call a screencast.

What OS are you on. There are screencasting apps by various vendors depending on your platform.

Here on MacOS I use ScreenFlow and it works quite well for me.

scorster

OBS Studio is another option and is cross-platform.

https://obsproject.com/

As you can see from the other responses, lots of tools out there for creating these types of videos. I personally use Screencastify, which is web-based and thus runs on pretty much any device. Loom is another popular choice in this category. Both make it extremely simple to record your screen and a thumbnail video of your webcam in the corner.

Since you mention "pictures of the scores I am using", I'm guessing maybe you are entering music from a pre-existing score, and you wish to show that as well? Simplest way to set that up would be to have a PDF or image viewer up on your screen at the same time, and have MuseScore take half the screen, the viewer the other half. But, a better way might be to create a blank score with nothing but a title frame, then paste the image of your score into the frame, and use the Documents Side-by-Side or Documents Stacked option the View menu of MuseScore to show both your real score and the picture at once. Less wasted screen space compared to having two windows open at once.