I know a lot of guys are probably hung up on any touching back there but they are really missing out. Especially if you are looking for some new thrills in your masturbation, take a look back there.
I have found that there are several very stimulating aspects of the anus. The outside is very sensitive and can feel really good with light rubbing. When it is relaxed, it can be really exciting to feel something enter the anus. Especially a finger or two. The prostate gland is where your orgasm comes from, and massaging it inside your anus is like nothing else you have felt. When the anus is fully relaxed, having it filled up with something, or having that pulled in and out is exciting.
The thing I don't like about anal is that it can be dirty. Any smell or sight of feces turns me off. So I usually only play with it after I've had a good bowel movement. You also need to be careful and use plenty of lube to enjoy it. Otherwise it will hurt, and that also turns me right off.
I wear a disposable rubber glove. It feels smooth and slippery and makes clean-up easy. I usually use KY jelly or something like that for lube, but there are better lubes out there for anal play. Some have desensitizing or numbing stuff in them. I think this is crazy because you could not feel if you were getting hurt, and duh, don't you want to feel all you can? Also be careful about what you insert. It needs to be very smooth and rounded and hopefully somewhat soft. You can injure yourself or get something stuck in there if it breaks off.
I like to put down a towel and get on the floor on my knees with my rump also down by the floor, leaning forward. Almost like I'm in a ball resting on my shins. I like to look at sexy lingerie photos while I'm doing this. I reach my right hand either up between my legs or around under my rump. Put some lube on a finger and just start touching around the outside of the anus. It feels really good if you let it. I like to rub in circles and tease the opening. Try squeezing your butt muscles or pushing like you are having a BM and see how it feels to your finger. I'll then add a little more lube and start working it into the opening and start slipping that finger in a little bit. This is where you can start working on relaxing, contracting the anus and see how it feels on your finger. You can learn from doing this how to let it relax and open comfortably. It is really like a vagina, it's closed much of the time and can be really tight but also can relax and open comfortably. Feeling the anus squeeze on your finger is exciting too, it's like when you first finger a vagina. As it relaxes, it can feel really exciting to take one finger and go in and out.
I will keep adding lube and try to work it up into the anus and soon, one finger will go all the way in easily. I feel toward my balls for the prostate and start to rub it. this feels so good and can cause semen to start drooling out of the penis. Soon one finger feels loose and I start trying to work 2 fingers in. It is like tight all over again but soon expands to accept 2 fingers. When I can get my index and middle finger all the way in, I can really massage the prostate. I like to put a little lacy black bra I stole on the towel to catch the semen drooling out of the end of my dick. Seeing it dribble out in a white string onto the black bra turns me on. At that point I want to use a toy I have. It is soft jelly rubber about 5' long and flared at the bottom. It has bulges on it that start out about 3/4' and the bottom part is about 1.5'. Sometimes I warm it up in hot water (not too hot!) before. The tip of It will usually go in easy, and then I can work it in and out until the larger parts will go in. Add more lube as required. This is where it feels so good to pull that in and out. It is kind of big, so it feels very 'filling' and it has the bulges that stimulate the opening and the sensation of insertion is always changing because of the bulges. Angle it toward the prostate and wow. At his point I have usually lifted my rump off the floor and sometimes I almost stand up bent over to feel the different sensations. When I'm ready to come, I start rubbing my cock with my left hand and do different things with the toy in my butt. sometimes rubbing my cock in rhythm with the toy moving or sometimes I just kind of sit down on the toy. Riding it up and down or just putting my butt all the way down on it. As I come I often let it slide out. sometimes it's almost like another orgasm. Maybe it's pressure on the prostate being released does it?
When it's done, sometimes the anus will feel a little tingly or sore. This is not totally unpleasant. Probably how a vagina feels after a good pounding. Sometimes I put a little vaseline on my anus afterwards to soothe it.
I say to just explore and see what you like and enjoy the anus!