Ok first of all, if you are really 12 years old, you should be SUPER SUPER proud. This is absolutely amazing work!
I remember when I was 14 years old (long long time ago) and I made my first game, I just wanted to show it to the world. It was a silly little asteroid shooter game but I was the only one that really played it. (This was before itch.io and other platforms to easily share your games).
How did I record your game? I used OBS :-) It's free software you can use to record your desktop. Works great, highly recommend.