How to open a book
There are two ways to open a book. One is to click a book in the shelf mode. And the other is to open a file in the book mode.
Click a book in a shelf
Select the shelf mode
Click the 'Shelf Mode' button in the toolbar.

Select a book
Click a book in the bookshelf.

Open a file
Select the book mode
Click the 'Book Mode' button in the toolbar.

Select a text file
A file can be opened either by selecting the file in the file selection dialog which is invoked by clicking the 'Open Text File...' button, or by dropping a file in the book screen. A text file (*.txt) or an EPUB file (*.epub) can be opened.
File selection dialog

Drag & drop

Set document format
Selecting a text file invokes the 'Set Document Format' dialog.
In case of a text file, Select 'Character Set' and 'Text Direction'.
In case of an EPUB file, Select 'Text Direction'.
Clicking the 'OK' button displays the text file as a book.

(Note: If the selected character set doesn't match to the actual character set of the file, the file will not be displayed correctly. In case of an EPUB file, a character set defined in the file is automatically used.)