Not sure what you mean by database files. Markster was following the
wikibooks tutorial or possibly the updated version on
superfamicom.org.
I never had much luck with tutorials beyond setting tools up at the very beginning. I've found that they tend to either gloss over important details or simply expect too much foreknowledge from a beginner. A typical path is to first learn how the CPU operates and behaves, then onto how it communicates with other components like the PPU and APU. One option is to grab a few of the debugging emulators and mess around with the features they offer.
Raw documentation is good, but there is an awful lot to take in. Being exposed to terms and skimming through specs can improve your familiarity with the system dramatically. The best documents to have on hand are
WDC's comprehensive CPU reference and programming manual,
Anomie's docs (particularly the register one) and
Fullsnes. Download them and when you have the time pick a page and start reading. Don't worry if you don't understand it all; if your head starts to hurt that just means you're learning.
The next problem is that knowledge doesn't immediately translate into practical skills. It's a good idea to get familiar with the toolchains for development, either oriented towards homebrew or romhacking; assemblers, tile editors, debugging emulators and so on. Prior programming experience can be beneficial but isn't essential. You might find that a lot of tools are good for some situations but don't really work as well for others. In these situations it's useful to have at least some ability in utility programming, so you can write your own tool that does exactly what you need. I don't think it's quite as common now, but it used to be very normal to find tools or documents older than you are that a lot of people swear by despite not being very good. What was best for a specific task twenty years ago might not be what's best today, despite what some people think.
Ultimately this can be a very rewarding journey and writing a halfway good game can be a very attainable goal, but by no means an easy one.