1. Go to this page and download the library: Download cubits/cubits-php library. Choose the download type require.
2. Extract the ZIP file and open the index.php.
3. Add this code to the index.php.
<?php
require_once('vendor/autoload.php');
/* Start to develop here. Best regards https://php-download.com/ */
$response = $cubits->createInvoice("EUR", "42.95", "Your Order #1234", array(
"description" => "1 widget at EUR 42.95",
"reference" => "my custom tracking code for this order"
));