Please be sure you know how to open a .ZIP file and then install and use the .EPUB or .MOBI files on your eBook reader before purchasing.
You should consult the user guide or support website for your eBook device for installation instructions. Some things you can try:
Our eBooks were sent to you packaged within a .ZIP file folder, so the first step is to open the .ZIP file. On Microsoft Windows or Mac OS X, simply double-click the .ZIP file, and then drag-and-drop the .EPUB and .MOBI eBook file out of it.
Apple iBooks on your iPad or iPhone will use the .EPUB eBook file you received from us. You can add them to your iTunes library by choosing File > Add to Library, or drag-and-drop the .EPUB file into the Books library. Then, sync iTunes to update your device. Click here for Apple support information.
Your Amazon Kindle will use the .MOBI eBook file you received from us. Click here for Kindle support information.
Nook (Barnes & Noble)
Your Nook will use the .EPUB eBook file you received from us. Click here for Nook support information.
Your Kobo will use the .EPUB eBook file you received from us. Click here for Kobo support information.