How to create a new library and use it with controller?

I am writing a very big application and I think it would be great if i could put that in a library and use it in my controller. How can I easily build up a simple library and use that in my Controller?
Care to give me an example?

Example:

PHP Code:

<?php

namespace App\Libraries;

/**
 * Class ExampleLibrary
 *
 * @package App\Libraries
 *          
 * in your controller or where you load the library
 *          
 * use App\Libraries\Example;
 */
class ExampleLibrary
{

    /**
     * Class properties go here.
     * -------------------------------------------------------------------
     * public, private, protected, static and const.
     */


    /**
     * __construct ()
     * -------------------------------------------------------------------
     *
     * Class    Constructor
     *
     * NOTE: Not needed if not setting values or extending a Class.
     *
     */
    public function __construct()
    {

    }

    // -------------------------------------------------------------------

}   // End of ExampleLibrary Library Class.

/**
 * -----------------------------------------------------------------------
 * Filename: ExampleLibrary.php
 * Location: ./app/Libraries/ExampleLibrary.php
 * -----------------------------------------------------------------------
 */ 


What did you Try? What did you Get? What did you Expect?

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In your controller, use

Code:

use App\Libraries\ExampleLibrary;

above the class
and then you can instantiate your library class in a method with

Code:

$exampleLibrary = new ExampleLibrary();