This How To video walks you through checking an Error message on your Apple AirPort Router.
Some times your AirPort router will have a flashing Amber light instead of a steady Green light. The Amber light is an indicator that something may be wrong with your AirPort router. To check what the Error may be you need to check the status message in AirPort Utility.
If you have an AirPort router and need some help setting it up watch our video How To: Set up an AirPort Router