App creation is such a simple process in Papertrell. If you already have a Epub version of book available, you can straight away follow the below mentioned steps.
1. Log in to your account in Papertrell (http://www.papertrell.com).
2. In Dashboard , Click "Add new title".
3. Select "Import Epub" tab > choose and add the single epub file /multiple epub files based on requirement>choose any template "Blank Templates/Sample Templates/ My Templates" and click Import.
4. Storyboard page shown.
4. Click "Preview on Device" button.
Wohooo. App is created. Next step for you is to view the app in your device .
Refer to "How to Preview your app in device"