Now create your pages of your book as normal, making their sizes as follows:
Width = half the width of your book.
Height = the same height as your book.
Adjust your iFrame sizes in the HTML fragment on the main index.html to these sizes too.
You can make adjustments to the css and functions as you wish. Full details available on the Booklet Web Site here
I think it should be easy to identify how this all fits together from the code and where it is placed.
If you need any help installing, or want to clarify why something is where it is or what it does, please contact me and I will do my best to help.