Authenticate user Laravel

hi guys i have an simple application with laravel and i try to add a user Authentication to my app , this is my route.php file :

Route::model('task', 'Task');


Route::get('/login', 'HomeController@ShowLogin');
Route::post('/login', 'HomeController@doLogin');

Route::get('/logout' , 'HomeController@doLogout');


Route::group(array('before'=>'auth'), function(){

Route::get('/', 'TasksController@home');
Route::get('/create', 'TasksController@create');
Route::get('/edit/{task}', 'TasksController@edit');
Route::post('/edit', 'TasksController@doEdit');
Route::post('/create' , 'TasksController@saveCreate');
Route::get('/delete/{task}' , 'TasksController@delete');
Route::post('/delete', 'TasksController@doDelete');

Route::get('/task/{id}' , 'TasksController@show')->where('id', '\d+');

});

this is my HomeController.php ;

class HomeController extends BaseController {

public function showLogin()
{
    return View::make('login');
}
public function doLogin()
{
    $userdata = array(
        'username' => Input::get('username'),
        'password' => Input::get('password')
    );
    dd(Auth::attempt($userdata));

    if(Auth::attempt($userdata))
    {

        return Redirect::to('/');
    }
    else
    {
        return Redirect::to('login');
    }
}

public function doLogout()
{
    Auth::logout();
    return Redirect::to('login');
}

}

and this is my login.blade.php file :

@extends('layout')
@section('content')
<section class="header section-padding">
<div class="background">&nbsp;</div>
<div class="container">
    <div class="header-text">
        <h1>Learning Laravel: The Easiest Way</h1>
        <p>
            Showing a single task <br/> using route parameter!
        </p>
    </div>
</div>
</section>
<div class="container">
<section class="section-padding">
    <div class="jumbotron text-center">
        <h1>
            Login
        </h1>
        <P>
            {{ $errors->first('username')  }}
            {{ $errors->first('password') }}
        </P>

        {{ Form::open(['url' => '/login', 'class' => 'form']) }}
        <div class="form-group">
            {{ Form ::label('username', 'Username:') }}
            {{ Form::text('username')}}
        </div>
        <div class="form-group">
            {{ Form::label('password', 'Password:') }}
            {{ Form::password('password') }}
        </div>
        <div class="form-group">
            {{ Form::submit('Login', ['class' => 'btn btn-primary']) }}
        </div>
        {{ Form::close() }}
    </div>
</section>
</div>
@stop

when i input any username and password i got no error and i never login , and i redirect to login page and dd() always return bool(false), can any one help that , and explain more about Authentication in Laravel , Thank U :)

Edit

and this is my model/User.php and i dont add any code to this :

class User extends Eloquent implements UserInterface, RemindableInterface {

    use UserTrait, RemindableTrait;


    protected $table = 'users';

    protected $hidden = array('password', 'remember_token');

}

i create my user table manually