Some good reading about it.....
The most sensitive part of a woman’s vaginal canal is the first inch to two inches. It’s here that most of the nerve endings are located, so when you first enter her concentrate most of your attention there. The elusive g-spot can usually be found in this general area, on the top of the vaginal wall, a couple of inches in. Imagine a glass lying on the floor. If you reach your first two fingers into the glass at the top, i.e., toward the ceiling rather than the bottom towards the floor, you should find it. It is difficult to reach the g-spot through intercourse, so you will find it much easier with you fingers than with your penis. There are also some interesting dildos and vibrators with just the right shape to reach the G-spot. Move your index finger or your first two fingers in a "come hither" motion (as if you were asking someone from across the room to come over to where you are) and gently stroke her. When you touch her g-spot you may notice a more bumpy or raised area of skin, but you may not. The best way to know you’ve found this highly intense love spot is by her reaction. Where you look is not quite as important as when you look. Unless she is excited through and through, perhaps from a clitoral orgasm beforehand, it can be difficult to find the g-spot.
Stimulation of the g-spot can produce extraordinarily intense orgasms. As a woman is approaching a g-spot orgasm she may feel she has to urinate. This may immediately cause her to tighten up, stop, and pull back from the edge of bliss. If she can stay relaxed and keep going through that "have-to-pee" sensation it will pass and move on into deep waves of sexual delight. Encourage her to breathe deeply and regularly. She should urinate before intercourse begins so she can be more confident that the feeling that she has to urinate is a misleading feeling and can be safely ignored.
For most women it is difficult to reach a climax through intercourse alone. This is because the sensitive clitoris isn’t easily stimulated just by thrusting motions alone. Often the male partner goes over the edge into ejaculatory orgasm before the woman has had enough action to bring her to the heights of orgasm. If you touch her clitoris before and during intercourse, and if you’ve pleasured her vaginally by touching the g-spot with your fingers, the chances are much better that she will have a deep vaginal orgasm while your penis is inside her. Choose positions that will stimulate the upper vaginal wall and try some shallow trusting patterns to stimulate the g-spot. Learn the strokes that turn her on. Tell her how fabulous it is that she’s sensual and sexual. Let her know you adore her body and love to touch and kiss it for hours. Help her forget about trying to make orgasm happen and focus instead on thoroughly enjoying every moment of lovemaking.