Are you using WPBook Lite, or WPBook? You’ve posted in both forums.
WPBook Lite does not provide a canvas page for the facebook app, so it is not intended to show anything. That’s one of the differences between WPBook Lite and WPBook.
If you use WPBook Lite you cannot enter anything into the canvas app part of Facebook setup.
Switching between the two will only cause confusion, as different settings are needed for each on the Facebook side and the WordPress side.
If your blog doesn’t support SSL, you cannot use WPBook and can only use WPBook Lite, in which case you will not have a canvas page for your Facebook app.