I\'m somewhat of a noob, and not afraid to admit that, I\'m working on this project as a learning experience to get better with php and serverside script/ing handling.
I
Create a public URL at http://example.com/whatever.php, where example.com is your domain name and whatever.php is a PHP file that you can edit.
Then put this code into whatever.php:
Then in the Shopify admin you can create a new webhook and point it at http://example.com/whatever.php, and when you click the 'test webhook' button in the Shopify admin, Shopify will POST to your script above, which should in turn write the body of the webhook to your PHP error log.