If you have no or negligible knowledge, I'd advise looking up some basic programming tutorials first, as general as you can find. Things like the paradigms, code structure, if/else statements, variables, loops, etc. Then once you have an idea of what programming is about, see the next paragraph. You could probably use the ones at the C++ reference; even though the language is different, the same principles apply for pretty much every language.
If you have any knowledge of programming at all, I'd advise taking a peek into the Trainer Card script, learning what things in there do, and then work on modifying it. The best way to learn something is to do it. I don't claim to be anything even resembling skilled, but I managed to overhaul my own Trainer Card and also create a simple starter selection screen based on it just by tampering with the code.
Oh, and most importantly, have A LOT of patience. It will take a long time and require a lot of effort to become a Maruno at coding. Don't expect to be creating your own battles system any time soon. Start small. Good luck, broseph.