Pls help wit my Project

Pls i'm tryin to build a multi user chat system in java and i need help on how to do this......pls help THAHKZ

That is absolutely not how this works. Read the link in my signature on asking questions the smart way before you post again. And when you do, ask a specific question and post an SSCCE demonstrating exactly where you're stuck. Don't forget the code tags.

For simplicity, I would use a client server approach with a central server, and each chat user has a copy of the client. If you want simple one on one chat, then you can create pairs of clients who's input and output streams talk to each other. If you want a chatroom, you can use the central server to forward the messages out to the list of connected clients.