To define a book, click the New Book () button in the Option Books toolbar. This adds a new book in the tree control. By default, the book is named "BOOK" with a unique number appended to the end. When the new book gets added, the name is open, ready to be edited:
To accept the default name, simply press Enter. To name the book by some other, more meaningful name, type the name and press Enter. You can rename a book at any time simply by selecting the book, pausing, and then single clicking the book.