Hi there,
To confirm the process for this: if you have set up your Webhook URL in your account dashboard settings as per above, all you need to do is create a job using your account credentials and you will receive the Webhooks that simulate the job correctly.
I can certainly see why having the option to “Try it Out” for the Webhooks section is confusing and we will take your feedback on board.
Asa an aside, we also have a Postman collection as a starting point for creating test cases via the Sandbox, as per here: Public Postman Collection Now Available, which includes all the endpoints on the API Docs pages