According to the pilot, this was his first flight in this flap only, high performance glider. The glider was towed to 5,000 feet, where the pilot practiced pattern work as well as extending and retracting the flaps, from zero degrees to 90 degrees, while maintaining an adequate airspeed for landing. The pilot entered a tight traffic pattern at the airport and extended the flaps to 30 degrees. On the final leg of the traffic pattern, the glider was in line with the runway, and the pilot intended to extend the flaps to 45 degrees, but was unsure if he did so. When the glider was halfway down the runway, the pilot knew he had excessive airspeed and was going to land further down the runway than intended. Near the end of the runway, the pilot thought he landed so he pushed the controls forward in order to gain ground control, but the glider continued over trees past the end of the runway. Since the glider did not have enough altitude to safely turn back to the runway, the pilot landed it in trees resulting in substantial damage to the fuselage. The pilot stated that he accumulated 107 hours of total flight time in a glider, of which, no hours were in the same make and model as the accident glider. The pilot reported there were no preexisting mechanical anomalies with the glider.