Allow PING from Specific IP Address to Outside.

Juniper Screen OS. SSG5 v6.3

I am new to Juniper stuff. I have juniper firewalls that are pingable but I only want to allow specific IP Addresses to ping the Outside (Untrusted) interface from the outside network but only allow specific IP addresses. How can I do this from the GUI? Do I need build a Policy, if so can walk me through the steps? Thanks!