That's great to hear, and thanks for asking!
Basically I have a type called _PlayerData which includes a few variables such as the location of the movable x, and also whether a button is being pushed. The type is shared from each of the clients to the server. The server reads which of them if any is pushing their button. The server decides, based on who is pushing their button, how x should be moved. It then shares back the _PlayerData struct, which the clients read only to know where the x cursor should be located. That way the "game" itself takes place only in the server, sending updated location to the clients, who do not connect to each other or run the game engine themselves. I hope this is a good explanation, let me know if anything is unclear.
Also, I'm not sure if this is the best way to implement this, I have no real training in coding, so there may be a simpler or stronger/more effective way of achieving this. My goal is to get online play capability for a sort of rpg fighter (think pokemon in real time) that I've been creating, so I started with this very simple server example.