sending notification in pusher private channel to selected users laravel8

Question

I'm sending notifications using the public pusher channel in laravel8 .. How can I turn it to a private channel in order to send notifications just to the selected user.. which the admin selected from the dropdown menu?

here is my controller

 public function notification(MessageRequest $request){

        $data =[
            'title' => $request->title,
            'body' => $request->body,
//            'users' => $request->users,
        ];

        
        event(new NewNotification($data));

        return redirect()->back()->with(['success'=>'success']);

    }

My event :

class NewNotification implements ShouldBroadcast
{
    use Dispatchable, InteractsWithSockets, SerializesModels;

    /**
     * Create a new event instance.
     *
     * @return void
     */
    public $title;
    public $body;
//    public $users;

    public function __construct($data=[])
    {
        $this->title = $data['title'];
        $this->body = $data['body'];
//        $this->users = $data['users'];
    }

    /**
     * Get the channels the event should broadcast on.
     *
     * @return Channel|array
     */
    public function broadcastOn()
    {
        return new Channel('notification');
    }
}

this is layout:

  <script src="https://code.jquery.com/jquery-3.6.0.min.js" integrity="sha256-/xUj+3OJU5yExlq6GSYGSHk7tPXikynS7ogEvDej/m4=" crossorigin="anonymous"></script>
    <script src="https://js.pusher.com/7.0/pusher.min.js"></script>
    <script>
        $.ajaxSetup({
            headers: {
                'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content')
            }
        });
        // Enable pusher logging - don't include this in production
        Pusher.logToConsole = true;

        var pusher = new Pusher('e7a414640973c420f866', {
            // cluster: 'mt1'
        });
    </script>
    <script src="{{asset('js/pusherNotifications.js')}}"></script>

and javascript file is :

var notificationsWrapper = $('.dropdown-notifications');
var notificationsToggle = notificationsWrapper.find('a[data-toggle]');
var notificationsCountElem = notificationsToggle.find('span[data-count]');
var notificationsCount = parseInt(notificationsCountElem.data('count'));
var notifications = notificationsWrapper.find('li.scrollable-container');

// Subscribe to the channel we specified in our Laravel Event
var channel = pusher.subscribe('notification');
// Bind a function to a Event (the full Laravel class)
channel.bind('App\\Events\\NewNotification', function (data) {
    var existingNotifications = notifications.html();
    var newNotificationHtml = `<a href="`+data.title+`">
<div class="media-body"><h6 class="media-heading text-right">` + data.title + `</h6>
 <p class="notification-text font-small-3 text-muted text-right">` + data.body + `</p><small style="direction: ltr;">
 </small></div></div></a>`;
    notifications.html(newNotificationHtml + existingNotifications);
    notificationsCount += 1;
    notificationsCountElem.attr('data-count', notificationsCount);
    notificationsWrapper.find('.notif-count').text(notificationsCount);
    notificationsWrapper.show();
});

any help please,