How did you learn to write so well?

Practice. Lots and lots of practice. I wrote A LOT when I was a teenager. And all of those hours were not wasted, even if my stories never went anywhere. Those hours were sharpening me, teaching me how to write and how to find my own voice.

Also, by reading. Reading has deepened my knowledge about how to shape a story, how to craft character arcs, how to write a good first chapter, etc.