Laravel 5.1 adding Form And Html Classes

I am new to Laravel and using Laravel 5.1.

FatalErrorException in 88e08cd08566357f572303974c44bc50 line 4: Class 'Form' not found.

For the above exception I did some changes in my project:

. "require": { 
"php": ">=5.5.9",
 "laravel/framework": "5.1.",
 "laravelcollective/html": "5.1."
 },

Added in JSON and updated the JSON file.

In config/app.php:

'providers' => [ // ... Collective\Html\HtmlServiceProvider::class, // ... ], 

In config/app.php:

'aliases' => [ // ... 'Form' => Collective\Html\FormFacade::class, 'Html' => Collective\Html\HtmlFacade::class, // ... ], 

I have added this aliases, but it's still showing the above error. Please can anyone help me?