Pilot of an AT-6 reports a lapse in judgment and/or complacency during a recreational flight. The wrong CTAF is used to alert other aircraft in the pattern and the wrong pattern direction is used to the wrong runway resulting in a NMAC with another aircraft.

Narrative

I made a right base turn to the runway and then a right out after a fly over the field. Upon turning out I passed under another plane which I did not see. I was on the wrong frequency for the CTAF and believed I was flying upwind but I should have not 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 lapse of judgment in not following standard pattern procedures. I was clearly not fully engaged (thinking through) and complacent; which also explains my not being on the right frequency. I can not understand how I didn't think through my actions enough to feel intuitively the risk to me and others to fly right turns. Then I received a call form 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 lap 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 sunny day.