To preface this, I am a complete rookie on anything to do with server-side programming.
Vaguely speaking, I built an extension on my Shopify website that lets users adjust the position of images on a canvas they can purchase. I can compile all the positioning data in an object on the client-side, but I have no clue how to send it to the server and retrieve it after a customer makes an order.
I looked through Shopify’s storefront API and didn’t find anything that helps with attaching data files with customer orders.