anal first time

my boyfriend wants to do anal. We’ve never done it before and I’m really scared, I’m not sure if I want to do it yet. He told me to prepare just in case. How do I do that?? I’ve heard about pooping before but I’m scared that it’ll smell really bad or he’ll get shit on him or like in those anal horror stories where people can’t stop shitting 😂 I’m also worried that it’ll hurt but not as much as having an accident. Helppppp