Questions about Python Socket Communication.

Hello, I am currently studying Python. I'm studying Socket Communication Program Maybe because I'm not used to it yet, I don't understand well even if I take this and that from various blogs and open it, so I ask for your help.

I want to write a program that has a multi-connect server, clients, and clients send a specific string to the server, and the server receives this specific string and returns something again, but it doesn't work.

I'm really sorry, but if you fill out an example simply, I'll look at it and analyze it one by one!

Thank you for reading.