post https://api.yourdomain.com/coupon-codes/generate
Your REST API service needs to expose one public API endpoint which accepts POST requests and which will be called from FluxPanda server. You need to provide the full URL to this API endpoint once you install the coupon generator plugin from within your channel's admin panel.
The API endpoint URL in this page serves only as an example, you're free to formulate the URL to your liking.