Dear god, Mario Paint is terrible for this, but at least it can do it. Anyway, here's a rough base for that riff I made in that thread a while ago. First 16 bars, so if you count right, it should sound OK.
I bet I would have had a better childhood if I had owned mario paint.
Download the free PC version. Mess around, it's fun albeit tedious, since you can't copy-paste and edit extensively (everything needs to be done note by note).
Dude... that was highly repetative... Needs something in the middle to break it up a bit. The intro was great, and the ending bits were good. but, it just dragged on a bit long for me. unless you plan to cover it with lyrics or something