What file format is the eBook?
The eBook will be downloaded either as a .zip file or a .pdf. Please see the item description for the specific file type.
If the file format is a .zip, you will need an unzip software.
If the file format is a .pdf, you will need the free Adobe Acrobat Reader, which is available here: http://www.adobe.com/products/acrobat/readstep2.html