I'd say if she was really into pleasing you (like a good girlfriend should be) just mention it to her...but make sure you tell her YOU are fond of it, she may say, "ewww" if she thinks you think that....or watch a porn with it in it? My man just straight out asked me to do it lol It's a HUGE turn on for me, and at first I totally didn't think it would be...

It took my wife a long time to comprehend that anal play does not equal homosexual tendencies. I bought a few small toys and asked her to try them out. The most successful toy was a vibrating plug that stayed in place during intercourse worked well because she could feel the vibrations - and liked them.

Might try asking her opinion on watching that in a porn. Say something like you happen to come across one online and that is what was going on. And see what she comments first. Then if she says that is hot you know what to say. But if she is grossed out, you'll have time to regroup and think about what all to inform her on why you like it and why she shouldn't be grossed out.

I think you should just tell her "I enjoy anal play." Then describe what you would like to do together and see how it goes. Even if she doesn't respond the way you hope right away, you have opened the door to begin sharing more of your sexual desires. Ask her about her fantasies! You may begin to discover all sorts of wonderful things about each other! It is a process. I wish you all the best!

Just straight up tell her!

I'd say gradually work your way back during cunnilingus. Tease the taint, then go a little further. By that time, she should be pretty relaxed/excited and open to anything, unless she has a major hang-up, then she'll tell you (or at least give you enough body language - do pay attention), at which point, of course, you respect her boundaries. If that goes well, slowly start working a finger in while you are orally servicing her clit. See how she feels about anal penetration by her reaction.

If that has gone well, you can certainly discuss it. Or you can just keep trying new things and watching her reaction. Keep in mind, you need to really have her warmed up (again, I suggest oral) before you move onto anything else. You can also try working a finger in her butt during vaginal sex. Many women like the double penetration.

Later on, trying out a small plug (vibrating is probably better) with lots of lube. Obviously, make sure she knows what's coming before you slowly work it in.

Remember, she may not have done any anal play before, or she may have had a bad experience. The key is to earn her trust by respecting her boundaries and earn her lust by keeping her coming from other, more familiar activity before you start making and backdoor advances.

Now, if you are looking to be the receptive partner on ass-play, I think that usually comes naturally after getting her to enjoy receiving first. You can give her the opportunity to play with you simply by being accessible and providing verbal and non-verbal feedback when she is doing something you like.

Tell her your into that, and ask her if she's willing to consider it.
For some girls it's a huge thing to get over, others (like myself) had a really terrible first time experience and would really rather not go back there.
Go slow, and level up with toys or fingers to the real thing. Nothing worse than just going all out for it.