How to implement authorization and saving user data in the game Tic-Tac-Toe in Java?

Question

Java

Hello! I am writing a Tic-Tac-Toe game in Java as a Server-Client. Gui and the logic of the game itself has already been implemented. There is still something left. It is necessary that at the start of the game, the client connects to the server with a login and then the server saves the statistics of the players somewhere in a file (win / lose, game duration, date, etc.). Advise something well or what to find / study. Thanks in advance.