Your experience with anal for the first time?

I'm about to try anal for the first time and I'm kinda nervous...I've gotten fingered there before years ago and I hated it but my boyfriend wants to try it and I want to try it too. But I  just feel like there's always gonna be poop in there even after I pooped!! How do I clean it out? And will it hurt a lot? I need all the advice and tips I can get 😭😭😭