Here's a Stupid Question

PHP question:

How do you post information to the database? I need to add a form in the checkout page and I can’t figure out how CS Cart is talking to the database.

Please feel free to make fun of me for not knowing… but you have to tell me the answer if you’re laughing.

From what I can guess, most or all of the .php files on the server connect to the database through config.local.php. But I don’t see any straight GET or POST stuff. It’s pretty confusing when you don’t know much about php.

Thank you, Triplets.