Don't understand how to implement turnstile

I have a contact form and I’m deciding to use turnstile as verification. The widget shows up fine but I don’t get how to do the server side verification part. . I’m using the worker code here but it doesn’t seem to work.

How are you processing your form, on the server? PHP? ASP .Net? Something else?

Can you provide the responses?
Did you set up the website on the turnstile page ? defined the domain? defined the site and secret keys ?

It’s a simple HTML form that uses the mailchannels pages plugin to send responses to me.

I setup the website and defined the domain but I dont understand how to configure the worker for the server-side validation. What I’ve done is use the code for the worker from the demo and just change the secret key, nothing else.