Start by asking her to give you a rim job, well for sure she's giving you a blowjob right ? Then slowly teach her to finger you there to open her up in this thing, that's how I discovered that men likes it and I used to be conservative too, sometimes women are just hesitant to do it
To each their own but it's my professional opinion that the wrong ass is getting fucked here. I would prone and doggystyle her big round ass relentlessly!!!