Everyone loves to talk about the lousy first draft.
Nearly everyone gets it wrong.
Yes, ignore spelling, punctuation, grammar in your first draft.
But also ignore everything you know about writing except this: tell your story.
The primary purpose of writing without stopping, spewing an unrefined first draft, is to not give yourself time to edit, even to think.
Only time to feel.
If you’re totally completely helplessly lost about this “ebook” thing, I’ll try to answer the question “Where do I start?” as long as we agree that it’s akin to asking “I’d like to learn to play music; where do I start?” Far too vague to have a real answer, but enough to start hacking through the underbrush to some better questions.