1. Go to this page and download the library: Download immonex/wp-free-plugin-core 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/ */
immonex / wp-free-plugin-core example snippets
$myimmonex_example_plugin = new My_Plugin( basename( __FILE__, '.php' ) );
$myimmonex_example_plugin->init();