What is the file name of my domain's main index page?
If you are updating the "main" page of your website, you are usually looking for a file named "index.html"
When accessing your web domain, you wouldn't need to type in the entire URL with the file name, by typing in your domain address (http://www.mydomain.com), you will be automatically forwarded to your main page.
In this case, make sure the page you are updating in the App also has the file name "index" (note lower case i). Some web host providers require this file to be named "welcome.html" instead of "index.html", please contact your web host provider if you have any questions.
After updating the page, please re-fresh your browser to see the updates. Sometimes, browser cache may still show you the older version, you may wish to close and re-launch the browser App to ensure you are loading the most up to date copy.