How to create (Use) SESSION in Codeigniter?

 Create (Use) SESSION in Codeigniter

Use in Controller

         $this->load->library('session');

$id=5;

        $this->session->set_userdata('ID',$id);

        redirect('dashboard', 'refresh');

        if ($this->session->userdata('ID') == TRUE)

        {

            //do something

redirect('dashboard');

}

else{

//echo 'hello<br>';

}