The private pilot executed a normal traffic pattern for a "wheels landing" in the conventional landing gear airplane. After touchdown, the pilot applied a "little forward pressure to the yoke to keep the tail up..." The pilot reported that the tail encountered a gust of wind from the left and he applied right rudder for correction. Subsequently, the airplane skidded off the left side of the runway and impacted a ditch. The right wing, right horizontal stabilizer, and fuselage sustained substantial damage. The pilot did not report any mechanical problems with the airplane.