The non-certificated pilot stated that when he took off in his airplane, it began to turn to the left. He was unable to stop the turn and the airplane stalled and impacted the ground. The pilot said that he just purchased the airplane and this was his first flight. He had not received any training in the airplane prior to the flight and had not received any recent flight instruction in any aircraft. A postaccident examination of the airplane revealed no pre-mishap mechanical discrepancies that would have precluded normal operation.