Trying anal stuff with my boyfriend

Hey guys. So my boyfriend is bisexual. He's dated and been sexual with both men and women. He's topped, he's bottomed, all that. I asked him if he enjoyed bottoming and he said he liked different things about both topping and bottoming. But his orgasms with bottoming were more intense. So I was wanting to try to Top him lol. I've never had anal done on myself let alone done it to someone else, so is there some advice on things I can do. How do I keep from hurting him? Things I should do to warm him up?