Here's a quick guide to creating a book in the GitHub writing mode on Leanpub:
1. Go here on GitHub and click "Use this template" to create a new repo with Leanpub's default book content
2. Clone the new repo locally
3. Create a new book on Leanpub and select the GitHub writing mode here
4. At this stage, you may need to validate your email address; in the end, you will be taken to the "Getting Started" page on Leanpub for your new book
5. Add Leanpub as a collaborator on the repo on GitHub
8. On the "Getting Started" page for your book on Leanpub, click on "Versions", and click the button to create a preview
9. When the preview is complete, click on "View the latest preview of your course"
10. At this point, we suggest you open the manuscript folder for the book in your local repo, and inspect the preview ebook files (PDF, EPUB, and MOBI) side-by-side with the .txt files you'll find in the manuscript folder, to see how everything works
11. Finally, please note that your book previews will be generated using the files listed in the Book.txt file in the manuscript folder. Changing the files listed there will change the files used to generate your previews
That's it for the TL;DR tutorial!
As a next step, at some point you may want to jump to this point in the full tutorial to learn about writing in your book, uploading a cover image, etc.