itch.io

I cannot find a tutorial for the absolute beginner that shows how to create custom character sets and screens for  game from start-to-finish?  How are binary files imported by, say a KickAssembler program and how are they used? How would my .asm project import and use charset attributes for example. By all means point me to a link for a  good tutorial for beginners, preferably with a working project in git that can be studied.