You show her how pleasurable it can be.  A few tips:

1. Baby steps…don’t bring up the end goal…get her talking about it.  Tell her you really want to explore how pleasurable her ass can be for her. Don’t make it about how badly you want to get inside her tight ass….if she was going to do it for you she would have done it by now.  You need to enlighten her with what she’s been missing out on.  Make it about her not you.   Assure her that you will go so…no penetration until she is ready.

2. Plan a special night where she is aware that you will start exploring her ass.  Don’t expect to just ambush her with assplay.  Chicks need to feel clean and prepared for sex.  If they are worried about odor, cleanliness, etc…be prepared to be shut down.  The key to anything anal is for her to be relaxed.  (If she seems concerned with cleanliness, there are some tips and videos in the link below.)

3. Start with your usual foreplay and some massaging to get her relaxed.  Spend lots of time teasing her pussy using some light touching and rubbing around her asshole.  Her pucker is a bundle of nerves that will drive her crazy.  Get her to flip onto her stomach.  Massage her ass every once and a while spreading her cheeks to hold her ass open for your inspection.  Groan like you’ve just seen the most erotic sight of your life to eliminate any self consciousness.  She will feel vulnerable but oh so naughty to know you are so turned on by the sight.  Continue to rub and tease until she is arching for more.   Place a few kisses on her ass cheeks…even a little nibble…get your hot breath close to her asshole and if she doesn’t shy away…lick.  There really is nothing as delicious as a hot, wet tongue against your asshole.  Finger or rub her clit while you do this and give her a wicked hot orgasm. 

4.  Afterwards talk to her about how she liked it.  Determine is she is happy to keep the assplay at that level or if she is ready for more.  When she is ready to try penetration start with the same prep to get her relaxed and turned on.  Use anal lube and rub a generous amount onto her hole.  Rub it continuously…think of her hole like an elastic…if you work it enough it will loosen and stretch.  Your finger tip should just slip in when it’s ready.  Don’t go any further….it can take a virgin ass a few minutes to fully take a finger.  Just hold it in her ass and work it in really, really slowly.  If you don’t do it right it will hurt.  Game over.  You got one shot to make it good for her so do your home work about assplay. 

5.  Check out my assplay advice page below and learn your stuff…it will pay off in the end.  Better yet…try it on your own ass first so you know first hand what she will be feeling!  Lots of couples explore assplay together…it puts them on a level playing field…you could always suggest that to her.

http://www.boyboygirllove.com/peggingassplaygirlcocks.html

Good luck hon!  :) xoxoxo