Whats the best postion for first time anal sex?

you need to build up to it try using smaller toys first then go bigger
And use a vibrator at the same time and focus on the pleasure then the pain disappears

Advice for women: Take control of your sexuality and preparation instead of relying on a partner to do everything; this is the single biggest mistake most women make. If you want your first anal experience to be more positive, masturbate anally for at least a few weeks - or months - with a small glass toy and water-based lube.

Poop prior to anal play, use an enema, begin masturbating vaginally, and apply lube to toy. As you get close to orgasm, lubricate a finger and massage it around your anus and then inside (having a vaginal or clitoral orgasm will help relax your anus).

Progression: Start with just shallow entry using a thin, glass toy. After a few sessions, you'll notice you can relax more easily to better accommodate the toy. Go a little deeper next time. Continue this progression until you can comfortably accommodate a good length. Once here, you will have graduated to another toy with more girth. Repeat the above steps until the toy you can comfortably accommodate is at least the size of an average penis.

You need to practice alone with a good toy. Slowly work it into you over a comfortable period of time.
You know the pushing you do to go to the bathroom ? #2 ....push like that as something goes in your anus. With lots of practice it gets way easier and then pleasurable and finally you learn to just relax and love it.
Now your ready for the real thing.

you face any problem first time .

me too i need a thin penis and was great