The pilot reported that on the first approach, the windy conditions affected his alignment to the runway, so he chose to perform a go-around. On the second attempt, the alignment was good, and the approach seemed normal until the flare. The pilot said that he flared the airplane a bit too much. He heard the stall horn sound, and slightly pushed the yoke forward. The airplane dropped fast for the last few feet and the touchdown was hard. He taxied to parking and tied the airplane down. It was dark and he did not expect or notice any damage. The next morning, his instructor called and asked him if he had experienced a hard landing. Examination revealed a buckled firewall, and sheet metal damage on top of the wing.