Remember to always use lubricant, the anus is not self lubricating. We recommend you use Astro Glide and Waxaline as they are both latex friendly lubricants.
When having anal sex you MUST stop at the very first sign of pain, if your partner is too tense to experiment, all forms of anal penetration will hurt him/her. So go slow, use lube, and only go in as far as their body will let you.
When experimenting with anal sex for the first few times, go very slow, after the recipient empties their bowels, slather lube over your finger and their anus. Put your finger on their anus and gently push, but do not go in unless they relax and let you in. There is no rush and if you take your time you will probably both enjoy the experience a great deal better.
There should not be a great deal of forcing required, when lubricated properly an object should slide in some what easily. We recommend using your fingers ahead of time to loosen them up first for toys and larger objects.
As with any sexual activity, communication is key to success so talk about what you want to do, so be open about your preferences and feelings, and be receptive to theirs.
Remember the rectum is used to empty feces from the body, and small amounts may still be in the rectum, so use a condom during anal intercourse, or prep your lover with 3 deep enemas.