Do you know how to program in PHP? Do you know database programming?
If the answer is yes to both the questions then you should start to design the database, interface and everything in between on paper to get an idea how to do everything. After that you can start with small parts of the design and test often, debug all the time.
If you answer no to any of the questionsabove then do a few tutorials to learn the basics. After that you should start with something smaller to learn everything, what about a register for your books with title, author, publisher and maybe a category? You will learn how to design everything by doing this, and it will be worth the time.