FEMA Independent Study Program, IS-248: Integrated Public Alert and Warning System (IPAWS) for the American Public [open html - 45KB]
"The integrated Public Alert and Warning System (IPAWS) Program Management Office designed this course to provide the American Public with an introduction to IPAWS. It identifies the key features and benefits of IPAWS and the authorities responsible for sending alert and warning messages. It also describes the actions you can take before and during an emergency to protect yourself and your loved ones."
FEMA Independent Study Program: http://www.training.fema.gov/IS/