1) Select a firewall in NSM Inventory to navigate to Firewall View>Monitor

2) Navigate to Alerts & Notifications>Rules and click on +Add Rule button; this will take you to Add Rule dialogue
3) In Add Rule dialogue fill in the Rule Name and select Web Activities and Websites from the Alert/Sub type dropdowns. In websites fill in the websites you wish to have trigger the alert.

4) Click Next and select the preferred notifications and history settings.

5) Click on Next to Review and Save your alert.
When the website is accessed, an alert will be seen as follows:
