First, you need a notification that tracks Webhooks, in the notification's Track step pick webhook and save it. If it's a is a new notification, be sure to finish creating the notification (read more here).
Connect to Cardcom
Follow these steps:
Go to your Cardcom settings, under "הגדרות למפתחים", set "Notify URL האם לבצע וידויי עסקה" on "פעיל"
Get your Webhook URL from ProveSource (from the notification details page, or from the "New Notification" wizard, see here)
Paste your ProveSource webhook URL under "לוידויי עסקה URL כתובת"
You're good to go!