Firstly you need to go to the root directory of your application and run:

$ sudo composer require intervention/image

this will download all the necessary dependencies that you need. Then  open your Laravel config file config/app.php and add the following lines.

In the $providers array add the service providers for this package.

Intervention\Image\ImageServiceProvider::class

Add the facade of this package to the $aliases array.

‘Image’ => Intervention\Image\Facades\Image::class

Now the Image Class will be auto-loaded by Laravel.

Publish configuration in Laravel 5

php artisan vendor:publish –provider=”Intervention\Image\ImageServiceProviderLaravel5″

you can check here for more info