Publish changes. Subscribe on changes. How to think?

I have read many articles and watched many tutorial videos, but the common ground for most of the material is to Publish changes to ALL users. Not Subscribing and get information what concerns just the user who is logged in.

The other common ground is Websockets protocol. There seems to be many other ways to skin this cat (Mark Twain) and I have some doubt which one to chose.

What I am searching for is a way for the user to login and connect to a server (Websocket server?) and say something like
**“Hey, I am Joe, please keep me updated on MY stuff”.**

I have managed to set up a [websocket server](https://ws.go4webdev.org), but I only gets more confused how to proceed. How to think? The closest [I have found is this](https://www.freecodecamp.org/news/million-websockets-and-go-cc58418460bb/). But this is above my pay grade. I do understand nothing.

In this stage I am mostly interested in “how to think”? No language specific.

Any input or direction is welcome!