This page explains what HACCP is and how to develop a plan for your facility: http://www.extension.org/pages/Food_Safety_/_HACCP
If you haven't done so already, it's a good idea to obtain HACCP training. An introductory HACCP training will provide you with a better understanding of what you need to do to write your own HACCP plan(s). Trainings are offered by Extension Specialists across the U.S. To identify an Extension Specialist in your state, go to:
http://www.fsis.usda.gov/Contact_Us/State_HACCP_Contacts_&_Coordinators/index.asp

