Which message library to use?

[eluser]n0xie[/eluser]
Did you at least take a look at the example controller?

Code:

// Then if we have a message, display it:
$message = (validation_errors()) ? validation_errors() : $this->session->flashdata('message');

// Set message
$this->message->set('error', $message);

// load view
$this->load->view('auth/index');

// in your view:
echo $this->message->display();

As mentioned before you can style the output using a view partial. Add a view to the /view/messages/ folder with the same name as your message 'group'. For example your errors can be styled using error_view.php, as shown in the example.