I Want To Have Sex With My Sister

The title pretty much says everything. She's just such a little prude. She's never even had a boyfriend. I have pictures of her changing, I watch her in the bath through a crack in the door. I've let her see my dick a few times "by mistake" and I think she likes it. She always looks. I want to know how to get her to touch it. I tried leaving it out and hard while I "was sleeping" but she just looked at it from my doorway for a few seconds then she walked away.