A website that let user place an image and another user also see it? [ONLINE WEBSITE]

I’m having a problem understanding how to work with actual online servers to make other user see what another selected item. Let’s say the image is selected and placed at location x and y the program will save the name and pos x and y. So there’re like 3 variable saved to be used, right?

I’d like to make this image appear to other users as well. Like, when they get into/or are staying on the web and it has refreshed the page.

I watched some tutorial but they were talked about local server I need a step-by-step for something online. I’m thinking about Firebase and etc. but I don’t understand some video talked about setting up and they don’t talk about passing variable or reuse the saved data.

What should I do? How should I approach this? Maybe I can apply the knowledge to what I want to do if the tutorial is at least close to want I need. Can you please point me to the right source of information for applying it with p5.js project?