Do you need chapters? Not for most picture books. A simple book is one flowing run of pages, and that is all a lot of stories need. But if a longer story wants sections, chapters are there, and you can add them whenever you like.
Simple or chaptered
You choose when you create the book, but you can change your mind. Open the book's overview page and find "Book structure": press Simple for a flat run of pages (best for picture books), or Chaptered to group pages into chapters (best for early readers).
Adding a chapter
On the book's overview page, press Add chapter. A new chapter appears at the end, named Chapter 2, Chapter 3, and so on. In the page editor, each chapter has its own Add page button.
Renaming a chapter
On the overview page, press the edit icon on a chapter to open Edit chapter. You can change its Title, and there is a Notes box for side notes to yourself that are never printed. Press Save when you are done.
Moving pages and chapters
In the page editor's page list, drag a page to reorder it within its chapter, or drag it into another chapter to move it. To put the chapters themselves in a new order, drag them on the book's overview page.
Deleting a chapter
Every chapter has a Delete chapter control, with two rules to keep your pages safe. A chapter must be empty before it can go, so move or delete its pages first. And a book always needs at least one chapter, so you cannot remove the last one. When you delete from the overview page, we ask you to confirm first, because it cannot be undone. In the page editor's list the deletion happens straight away, so use the overview page if you want the safety net.
Chapters are about organising your story. Everything else, from illustrating pages to exporting, works the same whether a book is simple or chaptered.