How to create a room where people can gather?

Question

Software design

Hello everyone, I have a misunderstanding on how to implement the creation of rooms with a code by which people can enter the room itself.
I can’t find a ready-made solution and figure it out, and I don’t find any articles (maybe I’m looking badly, because the task is trivial).
In general, the task is as follows: the user enters his name, presses the button and a room is created, an access code is generated. Another user can join the room if they enter the code. How to do it?