My harmonica learning story: After I started playing guitar in the mid-sixties when I was 15, I got interested in playing the harmonica, so I bought one and read the instruction sheet on where to place your tongue and blow out of the corner of your mouth, but no matter how much I tried, I couldn't get it.
I dabbled at it off and on for years and years. Then in the early eighties, working as a propman at Paramount Studios, I was assigned to a pilot starring Al Molinaro (Happy Days) and Lye Waggoner (Carol Burnett Show). One day when we were on a break from rehearsal, Lyle pulled out a harmonica and started to play (really good), then Al brought out a ukulele and played along, and the casting director stepped in with a soft shoe (he was a retired dancer).
When they finished I made a beeline to Lyle and told him I've been trying to learn how to play for years and just can't get it. He said he will show me the same way he was shown when he first learned it. He took my hand and put the flesh side in his mouth and played it like it was a harmonica. BAMM, that was all I needed, I got it instantly, pulled out my harmonica and started to play. Simply it was just keeping my tongue soft up against all the holes except the one at the very right corner of my mouth. It really didn't take much to get good clean single notes. Any chance I got in breaks, I would play.
A few weeks later I was working on another pilot and one of the young actors heard me playing off in a corner. He came over, pulled out a harmonica and started playing blues, I mean really good. I was awed and asked how to do that. He explained about cupping the tongue inside the mouth to create a cavity, then uncup and cup to bend the notes. Again, didn't take me long to get it.
I hope this gives you a little insight to playing.