In order to compile your website into a single working executable file for the desktop, HTML Executable needs source files (HTML pages, graphics, scripts...) to be available on your local computer.
A lot of offline website download tools exist like the free HTTrack available at http://www.httrack.com/page/1/en/index.html
Description from the publisher: "HTTrack allows you to download a World Wide Web site from the Internet to a local directory, building recursively all directories, getting HTML, images, and other files from the server to your computer. HTTrack arranges the original site's relative link-structure".
First, create a local mirror copy of your website with HTTrack in a folder on your computer.
Start HTML Executable, choose New Project, and select the index page of your website in the local folder created by HTTrack.
NB: you may prefer to keep your website online and create a custom-branded web browser for your end users to navigate.
