HELP ! How do you put in a tampon?

I'm 15 years old and i got my period in November ( i know really late) . Each month i have been using pads. I don't mind them at night. But during the day they are annoying, and feel gross, and are messy with my legs so i can't wear shorts. I love swimming and i'm an active swimmer. I want to learn how to use a tampon. But my mother won't let me, I stole a couple from my friends house. I want to learn how to use it, I know where it goes. But i don't know where to start How do you put it in the vagina? Does the plastic applicator go in too? How does it feel? Is it good for swimming? Can you bleed through on a heavy flow day? Does it ruin bathing suits? Thanks guys. I sound stupid but I need help.