An AT6 pilot entered a CTAF airport on the incorrect frequency on clear day and had a near miss with an aircraft when he did not comply with this airport's established traffic pattern.

Narrative

As pilot; I made a right base turn to Runway 15 and a right turn-out after a flyover of the field. Upon turning out I passed under another plane which I did not see. I was on the wrong frequency for CTAF and believed I was flying upwind but I should not have flown right turns. I realized after flying out of the area what a terrible mistake I had made and had a bad feeling in my gut. I evaluated the events that led to my lack of judgment in not following standard pattern procedures. I was clearly not fully engaged (thinking through) and complacent; which would also explain my not being on the right frequency. I can not understand how I didn't think through my action enough to feel intuitively the risk me and other to fly right turns. Then I received a call from an acquaintance informing me of the near miss. As a result I have grounded myself to take full stock of my actions; the events of the flight that led to this serious lack of attention. I now see a series of issues with the 45 minute flight that likely contributed to the situation; all dealing with me; the pilot; getting into the plane without thinking through/planning for the flight; then being inattentive and complacent in flying on a nice sunny day.