The folder we will be sending you is in a zip format. Before you can upload your file to Amazon, you'll need to extract this folder using a utility like Winzip. If you have a zip utility, clicking on the folder will automatically open it allowing you to open and save the files in different ways. Once extracted, you should be able to open the folder and see three files in it;
We used to supply customers with both an ePub and a mobi file which is one of Amazon's e-book formats. That no longer necessary since Amazon now accepts ePub files for uploading.
Please note that the best way to preview your book is to upload it to your Kindle (after converting the ePub using Kindle Previewer) or whatever eBook reader you are using. Any other application you use to preview your book such as Adobe Digital Editions or Calibre and even the Amazon site preview itself, may look slightly different.