Add NotificationBundle in your composer.json:

{
    "require": {
        "yit/notification-bundle": "dev-master",
    }
}

Now update composer.

Composer will install the bundle to your project's vendor/yit directory.

Enable the bundle in the kernel:

<?php
// app/AppKernel.php

public function registerBundles()
{
    $bundles = array(
        // ...
        new Yit\NotificationBundle\YitNotificationBundle(),
    );
}

Add the following configuration to your config.yml file

# app/config/config.yml
yit_notification:
    note_user: pathToYourUserBundle\Entity\User

###Step 4: Import NotificationBundle routing files

# app/config/routing.yml
yit_notification:
    resource: "@YitNotificationBundle/Controller/"
    type:     annotation
    prefix:   /

Now that the bundle is configured, the last thing you need to do is update your database schema.