How can i access my db_config.php file from index.html?

So i am putting together a basic website with a database backend. I have a database together, however i have been reading around a lot that for obvious reasons you DON'T want to store your database credentials anywhere in your public_html.

I have created a page "db_config.php" with my database name, username, password. And i have created a folder "config" ABOVE public_html to store it in. However i am having a hard time targeting it?

I was just wondering how i would go about targeting that file and parsing it into my database login? I have found a few tutorials regarding the matter but nothing that i have managed to get working with my project?

Would anyone happen to even have a link towards a basic tutorial outlining the necessary infrastructure? Thank you all for your time!