Anal sex takes practice to get right. You have to start slow. Sex is only erotic if you like the person you're doing it with. Otherwise, it's torturous.
Lube is an artificial fluid rubbed onto the p**is so it doesn't hurt you when it goes in. It can also be applied to the rectum. If lube is not used in anal sex, you could severely hurt your partner. Anal bleeding is a guarantee.