Rooms in sicket.io. How to send messages?

I am new at node.js and socket.io, following the 'get started' code from official socket.io website, I wrote simple chat. Then I wanna create different rooms, like in messengers. But relying on official documentation, I can't do this as myself... Here is my server code:

io.on('connection', function(socket) {

    var room_name = socket.request.headers.referer; // link of the page, where user connected to socket

    // connecting to room
    socket.join(room_name, function(){
        //trying to send messages to the current room
        io.to(room_name, function () {
            socket.on('chat message', function (msg) {
                io.emit('chat message', msg);
            });
        });
    });

});

And my client side code:

        $(function () {
            var socket = io();
            //when we submit our form
            $('form').submit(function(){
                //we are sending data to socket.io on server
                socket.emit('chat message', $('#m').val());
                $('#m').val('');
                return false;
            });
            //And then we are creating message in our html code
            socket.on('chat message', function(msg){
                $('#messages').append($('<li>').text(msg));
            });
        });

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