This page describes how to setup an account for development/test environments with Authorize.Net.
Register for a free sandbox account at https://developer.authorize.net.
Following registration, login to your sandbox account at https://sandbox.authorize.net.
Navigate to Account > Webhooks
Click "Add Endpoint"
Fill in the form with the subsequent values:
Under selected events, select only All Events > Payment Events > net.authorize.payment.authcapture.created