Assign a Role with FosUserBundle

I'm really new to Symfony, I'm trying to register a ROLE to a User with FosUserBundle but I can't manage how to do it. Actually I integrated also PUGXMultiUserBundle in order to have two different form for two different roles. Can anyone help me?

Thanks in advance

--UPDATE--

I report my code in order to explain clearly. I create this files with the guide of PUGXMultiUserBundle

This is my entity:

//C:\BitNami\wampstack-5.4.23-0\frameworks\symfony\src\Acme\ManagementBundle\Entity\UserGroundStation.php
<?php

namespace Acme\ManagementBundle\Entity;

use Doctrine\ORM\Mapping as ORM;
use PUGX\MultiUserBundle\Validator\Constraints\UniqueEntity;

/**
 * @ORM\Entity
 * @ORM\Table(name="user_GroundStation")
 * @UniqueEntity(fields = "username", targetClass = "Acme\ManagementBundle\Entity\User", message="fos_user.username.already_used")
 * @UniqueEntity(fields = "email", targetClass = "Acme\ManagementBundle\Entity\User", message="fos_user.email.already_used")
 */
class UserGroundStation extends User
{
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;
}

And this is the controller

C:\BitNami\wampstack-5.4.23-0\frameworks\symfony\src\Acme\ManagementBundle\ControllerRegistrationController.php
<?php

namespace Acme\ManagementBundle\Controller;

use Symfony\Bundle\FrameworkBundle\Controller\Controller;

class RegistrationController extends Controller
{
    public function registerUserGroundStationAction()
    {
        return $this->container
                    ->get('pugx_multi_user.registration_manager')
                    ->register('Acme\ManagementBundle\Entity\UserGroundStation');
    }
}

Sorry for the dumb question, but it's my first project and I feel a bit misplace.

--UPDATE--SOLVED--

I found the solution here Sorry for the redundance of the question, I didn't find it by Google.