Create Virtual or Sub Bookshelves To Organize Your eBooks

1.  Click the down arrow next to "BOOKSHELF"

2.  Now click "Create Bookshelf"

3.  Specify the name of your bookshelf 

4.  To select the books to be added to your bookshelf click "Select Books"

5. Now select the books you want to be added and click "Bulk Edit"

5. Now assign the selected books to your desired bookshelf.