how to program PK3 key on 2001 Pontiac Aztek

I have a PK3 key for my Pontiac Aztec. I had the SECURITY message show up on my dash earlier today. I shut the car down and when I went to restart the car would not start - however all other systems run. I am advised that this is a problem with my PK3 key.

How do I program a new key for my car when the car will not start now?

Asked by for the 2001 Pontiac Aztek