You now see a chapter and a sub chapter. Because we did not elect to number chapters, the fact that the second chapter is a sub chapter cannot be seen in the table of contents. Note that you do, however, see this in the title above the content.
By the way, the items in the table of contents are neither numbered nor are they indented only because that is the option we chose when setting up the book. We can always go back and change that.
In addition to the links in the table of contents, you may move through the book using the arrows located to the top-left and bottom-left of the content.