Booklet is the application which allows you to create a booklet from any PDF file. It handles right-to-left languages such as Arabic, Hebrew, Persian, and Urdu as has may other options to customise your booklet creation.
On how to open your PDF with the Booklet application please consider one of the following options bellow:
1. When you launch the application (click on it) by default it should present "Open file" dialog. If this dialog is not visible, please make sure it is not hidden by windows you have open from other applications.
2. Please make sure you have clicked on Booklet application, locate "File->Open" from the menu, click on it. Open file dialog should be presented in this case.
3. Drag your PDF document onto the Booklet application.