Never done butt stuff

My husband (m36) has.. but I (f34) haven’t. And I kinda wanna surprise him and just let him do it to me one night in the near future. However, I don’t want it to be awkward and hurt for my first time with him so I’d like to prep myself with a dildo that’s actually a silicone clone of his lol. Any suggestions? I don’t even know where to begin. I’m afraid I’m gonna poop on him or something. How do you prepare for spontaneous butt sex? Should I start with the dildo? He did it.. I’m kinda gonna feel like a lil b*tch if I don’t hahaha