In this chapter you learned how to build a user interface from the ground up, starting with the smallest unit (a tile) and building your way up to a small and large board. You included layouts from within other layouts, and defined styles to keep from repeating yourself. And you saw one way of communicating between fragments and activities.
The next chapter will add an AI to the game so it can play you (badly). If you want to skip that part, just copy the code from the website and move on to the chapters on animation (Chapter 7, Adding Animation) and multimedia (Chapter 6, Adding Sounds).