Mario Paint's Stamp editor mode along with the Nintendo Power "Player's Guide" (if you can call it that).
There was a section in the middle that showed you how to make sprites from zelda, Street fighter, and a bunch of other crap.
A few weeks later, I found MSPaint. Then, quite a long time later, I found the original Pixelation tutorials.
As for the Mario Paint date, I think i got it for Christmas of 1992, then I got the player's guide early spring of 1993.
I don't remember when I found out how pixels worked the same as the Stamp Editor in MSPaint, but I remember I was at my cousins house when I figured it out.