Go through spark the definitive guide, this book is very well written and explains all you need . "Sections I, II, and IV of Spark: The Definitive Guide and Chapters 1-7 of Learning Spark should also be helpful in preparation" as quoted on the main page but in my experience 'Learning spark' was a bit haphazard. Also try the practice exam provided as it gives a complete idea of what to expect and questions were similar, all books have notebooks attached with it, you can use community edition for practicing those.