From my posts below about debunking writing myths, it probably won't come as a surprise to hear that I haven't, by any means, read all the books ever written about the process of writing.
The best way to learn about writing, I think, is to just get on with it and write.
Oh, you need to read, of course; you learn from reading wonderful writers. That's a given.
But if you spend too much time studying writing, it can stymie your natural voice and natural skills and make you an imitator. Or trip you with too many theories and not enough practise. Or ensnare you in the convoluted business of studying writing instead of getting on with it. (I'm up on every procrastinatory technique, believe me!)
That said, here is an excellent book about the process of writing fiction. It discusses setting, character, plot, point of view, the shapes of a story, the process of editing, and much more.
I have a copy and when I get stuck over some writerly matter, this is my go-to book:
A PASSION FOR NARRATIVE by Jack Hodgins.
It is clear, insightful and comprehensive.