There was no tutorial for this on YouTube so I figured why not.
Software used:
loopMIDI (made by tobias erichsen): http://www.tobias-erichsen.de/wp-cont...
FL Studio: https://www.image-line.com/fl-studio-...
Any MIDI files you want to use you can probably find somewhere on the internet if you google enough, but here are some decent websites for videogame midis:
https://www.vgmusic.com/
https://www.khinsider.com/midi/