Thank you for the code.
I don't know why it isn't working for you, but when I added it to my X-Cart installation, it worked just fine. The module shows up in the list of addons
Screenshot attached.
Maybe you are inserting it into a wrong folder?
The path must exactly match the namespace, so you should be putting this into <X-Cart>/classes/XLite/Module/GreevesH/FirstModule/.