The html files regarding your site should be located at a path like: domains/DOMAINNAME/public_html
However, your site does not use .html files, it has .php files, which may hold a bit more logic then the .html files does, it appears you created the content using "sitepro" which means the content is writting in the php language as well.
Html is still used for the visual stuff but php is what is managing what should be displayed where.
If you are not familiar with php programming it won't be as easy to edit the content by editing the files, it would still be doable when you find the relevant file(s) and stick to altering the parts that are written with html.
Sitepro is no longer available under free hosting, but if you prefer to start over there is a website builder within the softaculous app installer. You could also chose to install wordpress or other CMS to handle your site which makes it rather easy to edit content.
