Hi I am super newbie, helping edit, and I just need to add a line of code to the index page (the templates are responsive but not detecting the devices?) Anyhoo when I try to access the index.html files it says unauthorized. Am I in the wrong place?
What version of ModX are you using?
The base file is typically index.php, and it is not a good practice to alter this as future updates will overwrite it.
A better method is to update the template in the manager. If you need to put a device sniffer in (like a PHP script) you'll want to put that in the template above the <html> tag to run prior to processing the HTML header.