Masturbation techniques

How do you usually masturbate? Like, I masturbate rubbing my puchie in the surface(is that still included? ) , is it normal masturbating ling that? Or not??and when did you know how to masturbate?? Like, I already did this when I was chuld like, about 2-3 years old and my mom always scold me for this, I don't know how learned this when i was kid but Is this normal??