Hi and welcome to the forum.
The nice thing with air pistols is that most of us can manage to have a safe, indoor range at home, so you can get plenty of practice in. There will be various excellent books you can buy, most probably from specialist target shooting shops, with advice on technique. Even without these, if you concentrate on consistent hold, attaining correct sight picture, SQUEEZING the trigger and follow through, take your time, relax.....you'll get there.
However, I think the best thing to do would be to try and suss out your nearest club. There you'll meet fellow enthusiasts, all sharing this common passion. Fantastic banter usually to be had. And you can glean tips and techniques from the better shooters, bringing your talents on.
There is also the Umarex Boys Club, which you could maybe look into, which runs and administers postal competitions etc...
I'm sure someone with more detailed knowledge will be along soon......