Um, I'm not gay and I've done girls in the ass.
I'm going to explain how to get a girl to anal. It will be somewhat graphic, so if you're offended by anal sex, please just skip my post.
My experience:
Did I like it? Yes. It's like a vagina except tighter.
Did she like it? Yes. Many girls don't think they will like it, but they just don't know how it would feel. Also, some have the fear that it could hurt (and it could if done wrong).
How did I persuade girls into trying it? Well one of the girls already knew she liked it and she was the first one I got to give anal to.
The others (2 others to be exact), I didn't tell them anything about eventually trying anal, but since I was dating them I had time to work them into it. Simplest way to start initiating a girl to learn to enjoy it is to slip a finger in while fingerbanging her. Before you do, you'll want to get it lubricated. So either put your finger in your mouth and get a lot of saliva on it. The more the better because if it's dry, it will hurt her and she will never let you go there again. OR, fingerbang her with that finger for a few seconds and just use her juices. Then slip it in while fingerbanging her with another finger.
DO NOT, I repeat, DO NOT stick the finger that you just put in her ass back into her vagina. She can get an infection from that. DO NOT do that.
Anyway, she'll enjoy getting both holes fingered. If you lick her **** at the same time and make her orgasm, she will have a more intense orgasm than normal due to multiple stimuli.
Also, if you're doing her doggy style, spit on her ******* (remember it's lubrication) and stick a finger in while you're pumping. It'll drive her nuts.
If you ever take a shower with her (cause it's a clean place to try this), you can start messing around and then start going down on her in the shower. Tell her to turn around and lick her ***** from behind and then move up a little and give her a rimjob. Don't worry it won't taste like anything (but don't stick your tongue in). Then when you come back up, you can start bringing up the topic. Ask her if she has been enjoying how it feels when you finger her ass and such. Then ask her to try anal once. She'll probably say ok (mostly because she's curious, just like you).
Wear a condom please (even if she's clean, just put one on).
Do it doggy. It's the least painful way to start. Start with regular intercourse in doggy and start using your saliva (by spitting) to lube her up and finger her ass. Then when you've gotten enough spit on there so that your finger feels like it's just slipping back and forth get ready to stick your **** in. Go SLOWLY. And I mean just a little at a time. If she says stop, you stop. Just go slow and ask her how it feels. Don't ask, "does it hurt?" You don't want her to worry or think about pain. Ask her if it feels good, or if it feels naughty or something.
Once you have pushed all the way in, you can start pumping slowly. Rub her **** if you can, if not, tell her to rub herself. She'll start feeling really good once she starts doing that and you can slowly increase the speed of your pumping. Keep going until you finish.
Afterwards you can talk about it and see if she'd like to do it once in a while.
There you have it. Anal sex. It's not gross. And always listen to the girl about if she wants to do it. She knows how she's feeling (bloated or like maybe she needs to go to the bathroom). So you can always just tell her to tell you when she wants it. And once a girl has a positive experience with anal, she'll probably want it again.