Welcome to the Fizl example. The whole structure of this site is being generated by flat files - either HTML or markdown (.md) files! Even the navigation above is auto-generated from these flat files.
You can find the file with this content in content/index.html.
The template being used to generate the home page is assets/templates/home.html.
To get started on your own Fizl site, you can either delete the files inside content and start from scratch, or edit what's there.