After you log in to your account, click on your email in the upper right corner and "My Settings".
Click on the “Add Integration” (or "Add Alert Contact") and choose Pagerduty Alert Contact Type.
Enter the Friendly Name of your contact and your Pagerduty URL (Integration Key). To get this from Pagerduty please follow the pagerduty.com/docs/services-and-integrations#generate-a-new-integration-key">Generate a New Integration Key instructions.