THE PILOT TOOK OFF ON A DARK NIGHT TO AN AIRPORT THAT HE HAD NEVER LANDED AT BEFORE. WHILE EN ROUTE, HE BECAME DISORIENTED AND CALLED A FLIGHT SERVICE STATION FOR HELP. A MILITARY HELICOPTER PILOT RENDEZVOUSED WITH THE LOST PILOT AND PROVIDED VECTORS TO THE DESTINATION. POWER LINES WERE LOCATED NORTH OF THE AIRPORT. MOST OF THE PILOTS THAT WERE FAMILIAR WITH THE AIRPORT PLANNED THEIR APPROACHES TO GO INSIDE THE POWER LINES. HOWEVER, THE PILOT OF N3563W APPROACHED OVER THE LINES WHICH NECESSITATED A HIGH PATTERN. ALSO, THE PILOT STATED THAT AFTER HIS EN ROUTE EXPERIENCE, HE FORGOT TO LOWER HIS FLAPS. WHILE LANDING, HE FLOATED AND TOUCHED DOWN ABOUT 500 TO 700 FT FROM THE DEPARTURE END. WITNESSES HEARD THE BRAKES SQUEALING AS THE PILOT CONTINUED OFF THE RUNWAY. AFTER DEPARTING THE RUNWAY, THE AIRCRAFT CONTINUED DOWN A GRADE AND INTO A GULLY AND WAS SUBSTANTIALLY DAMAGED. AN EXAMINATION OF THE AIRCRAFT REVEALED NO MECHANICAL PROBLEMS.