If you haven’t found him already on YouTube, I’d recommend essential craftsman. He did a whole series on building a house from leveling the ground and pouring foundations, right through to the finishing touches.
He did a couple of videos on stairs, I seem to remember he made a mistake on the heights so took everyone right through how to do it properly. I must admit I got a bit lost as he was working on Imperial rather than metric, but he did cover metric and it seems 100 times easier.