You can download Genesis, the first volume of the Readable Bible series, absolutely free here:
The Epub version is compatible with most eBook readers, including the Apple iBooks app, the Google Books app, Blackberry devices, Kobo eReaders, and almost all other major eBook readers and software apps.
The Mobi version is for Amazon Kindle devices and Kindle Apps. To transfer the mobi file to your Kindle device, use the ‘Send to Kindle’ app or email it to your Kindle device’s email address (instructions here).
The iBooks version is available for Apple devices in the Apple iBooks store.