Many video cards come with their own software that includes the ability to take screenshots and videos using keyboard shortcuts.
If you have an Nvidia card, then the program is called Gforce Experience, as Blady mentioned.
For my Radeon card, the program associated with it is called Radeon ReLive.
A great tip for free editing software that I picked up from someone at FGM is OBS Studio.
https://obsproject.com/
However, these days I've been using a program called Vegas Movie Studio 13, which I got on sale on Steam, of all places.
It has been easy to use and I was editing within seconds, without tutorials.
Once you have edited your movie, you export it to your computer.
Then you go to your youtube channel and go through the short process of uploading.
At the end of it, you get a link to post.