To summarize:
- Once you have one or more existing pages, you can create a book by assigning one of those pages to a new book.
- You can then continue to add existing pages to your new book, or create new pages for it.
- Although the individual pages do, your book does not appear in normal article lists. That's because your book intro page (or cover page) is not a normal article; it's a 'container' which holds your chapters. Your chapters are normal articles, which have been assigned to a given book container.