For the most part, there's one anal sex position in mainstream porn: the receiving partner bent over, somehow enjoying being jackhammered in the booty by a massive penis. While anal sex from behind can feel marvelous (and indeed provides fairly easy butthole access), it's neither the only nor the most pleasurable position for everyone.
But before you even choose a position and stick a penis or a strap-on dildo into an anus, you have to make sure that that anus is properly loved and cared for. That means starting small (with fingers, butt plugs, or anal beads and moving up to a penis or larger dildos) and using plenty of lube, since the anus isn't self-lubricating. Usually, a silicone-based lube is your best bet for butt stuff, because the rectum absorbs water rapidly. But if you're using a silicone toy for anal stimulation, you're better off using a water-based lube. (More on lube options for anal sex here.)
Once you've got all of that down, it's time to choose a position. Ahead, some of our favorite anal sex positions that will give you a sense of the variety of options out there. Find one that's exciting and comfortable for you, and don't forget to communicate with your partner throughout to make sure you're both enjoying yourselves.