That's basically it. From the description, you might think the penis person is having all the fun. That's no true. The ass-person may be enjoying even more pleasure. There are two reasons for this: the anus is very sensitive to erotic touch, like the lips; and the inserted penis will massage a small gland behind the testicles, called the prostate. When this gland is touched during sexual arousal, the pleasurable feelings are multiplied in intensity. Thus, during anal intercourse, powerful erotic feelings can flow all through the body around the genitals, anus, and internal organs; the rectum may begin contracting up and down in waves of pleasure, causing an anal orgasm along with the genital one. The penis-person can masturbate his partner; the ass-person can masturbate themself, or the penis-person can even reach around to insert a finger in his partner's anus - many possibilities are open for you to discover exactly what you like to do and enjoy, according to your different wants and moods.

In other words, if you're new to it, it's best to learn in steps and not to expect to know or do everything at once; usually it takes months or years to feel and shape the many potential desires and satisfactions. The basic act is simple, but our culture teaches us to be so inhibited about sex, gay sex, and asses in particular that some confusion may have to be worked through. Once you're over this, new levels of meaning will be open to you.