How to send messages to clients in Netty?

I’ve been writing a networking server I’ve been able to read messages from a client, but don’t understand how to write message to all connected clients as well as to 1 specific client.

I’ve looked through the netty docs but it only shows examples of sending a message right after already receiving it. Can anyone give me an example, or a good article that better explains this?

This is what I have so far.