Lesbian strap-on sex instructions.

Find the right dildo. Here are some tips for buying the right dildo for your needs.
Get used to your new toy. Put on your harness and dildo and get used to how it feels before jumping right into bed with your partner. Have her help you into the harness. The tighter it is, the more control you will have and the more sensation you will feel.
Don't forget foreplay. Kiss her. Touch her. Get her excited and turned on before you penetrate.
Put a condom on your dildo and use plenty of lube, even if she seems lubricated. Slippery and wet is much more enjoyable.
Go slow and easy the first time. Angle your dildo upwards, not back toward her spine. Let your partner guide you in how fast, slow, deep, rough or easy you go.
Try different positions. Old fashioned missionary position allows for face to face intimacy. Doggy-style allows you to penetrate further inside her.
Use your hands. Remember the foreplay? Keep at it, caressing her where she likes it most.
Mix it up. Experiment with oral sex. Watching their lover go down on a dildo is a big turn on for many dykes. If you want to experiment with anal penetration, take it slow and easy and use lots of lube. Remember to change condoms any time you change orifices.
Communication is key. As with any sex, talking about what you like, don't like, what you want, what feels good is very important. Listen and pay attention to her body language. Ask her if it feels good. Does she want it deeper, faster, slower?
Remember if you share any sex toy, to change the condom!

Tips for Strap-On Enjoyment

Strap-ons are more elaborate than your average sex toy, and stepping into one may feel odd. Take your time. The dildo needs to be fitted into the front piece and straps may need to be adjusted. Be patient with these toys, with yourself and with your sex partner. At first you may feel awkward.

Always use plenty of lubricant with strap-ons. Your dildo -- as well as any body part you’re planning to use it on -- should be generously lubricated before insertion. Experiment to see which one best complements your strap-on play.

At first, the wearer should refrain from thrusting, allowing the recipient to slowly engulf the strap-on dildo instead of being penetrated. The rear-entry (doggie style) position is a good one to use.

Strap-on harnesses allow the wearer's hands to remain free during erotic coupling. Use your hands in other places.

Some couples like to explore simulated fellatio in which the recipient sucks on the dildo. If the dildo has been inserted anally, it should be thoroughly washed with soap and water and/or a sex toy cleaner before it enters the recipient's mouth.

If a man wears the harness, he might alternate inserting his erection and the strap-on dildo into his partner.

If a man wears the harness and the woman is open to double penetration, the man can insert his penis and strap-on dildo simultaneously into her vagina and anus.

When women wear the harness, the front piece typically covers the clitoris. Some women enjoy the clitoral stimulation that results when the base of the dildo presses the front piece against it. Others miss direct clitoral stimulation. If so, reach under the front piece to fondle her clitoris. Or loosen the straps and lift the front piece or move it aside to allow access to her clitoris.

What is strap-on dildo?

Here is some information from wikipedia about strap-on dildos.

A strap-on dildo (also strap-on, dildo harness) is a dildo designed to be worn (usually in a harness) by one partner and used to penetrate another partner vaginally, anally or orally, used by both heterosexual and homosexual couples.

For a woman, a strap-on can be used to anally penetrate a man (pegging), or used vaginally, anally, or orally for lesbian intercourse.

For a man, a strap-on can be worn for penetrative sex, and may be used in cases of erectile dysfunction, for double penetration, or to penetrate multiple partners. A wide variety of harnesses and dildos are available, with different ways of fitting the wearer, attaching the dildos, stimulating the wearer or the receiver, and all with different features, advantages, and drawbacks for both users.