Learning A Lot

When I was very young, about 3rd grade, me and my sister and one of my female cousins had a sleep over. We all stayed in the same room in our apartment. I remember staying up and exploring each other's bodies instead of sleeping. My cousin was a little younger than me but said she saw her dad watching movies with naked girls and she remembered the stuff they would do. She put my penis in her mouth and made it hard and then licked my sister.
We went into the closet and got completely naked. She laid on her back and lifted one leg up over my shoulder and told me to rub against her with my parts. I did and after I found out about sex when I got older I was always so pissed of that I didn't know I was supposed to go inside her! I don't know if she or my sister remember it but I sure as hell do! We never talked about it again.