You have two pages, the main page and the search page. The main page contains 3 shelves which are Currently Reading, Want to Read and Read. You can easily move a book from one shelf to another or by selecting none the book will be removed. The Search page will allow you to search for the book you want and add it to one of the three shelves. If the book you want is already on one of the three shelves then you will see in which shelf it is.