Give that a go on your own before with a partner. Give yourself a nice couple hours to yourself just to play around with some lube on a towel. Get a pack of wet wipes and one of those "enema" kits from CVS to clean out before you do any insertion stuff (don't use the saline in the bottle, use warm tap water. The saline will irritate you. Look up a guide on Reddit for more info).

My girlfriend and I do a lot of pegging, and I do a lot of anal stuff on my own, and I know where you're coming from. Over time as you get used to it, you'll open up (ha) to different kinds of anal experiences.

I do just want to say that getting in touch with that part of my body was one of the most incredible experiences I've had as a man. The prostate is amazing, and once you get used to playing with it, it'll feel like discovering masturbation all over again.