How to locate Female G-spot
All records are extract from expert's advice... not mine..
It took me some time to compile these.... So please do not start unnecessary flaming if it doesnt work on you. 
After wetting your latex covered finger with saliva or water-based lubrication, slowly place two fingers into the vagina. Using your index finger, touch the anterior wall. It is approximately a finger length up. Many women like having the person touching them use their index finger to place some pressure on the wall. Try making the 'come here motion' with your index finger. Allow the tip of your finger to tap on the anterior vaginal wall. Let her level of excitement guide your movements. Talk with her, and ask her how different formsof touch feel. Some women may not like the feeling of being touched there and may even find it painful. Another way to tell if you are indeed touching her g-spot is that there will be a change in texture. The g-spot area will feel flushy, like a small area of wrinkled skin. In contrast, the surrounding area will feel taut. The shape of the g-spot is similar to an upright kidney bean.
In addition to touching her g-spot with your index finger, I encourage you to use your tongue (remember all those tongue exercises!) and stimulate her clitoris, inner & outer lips. The combination of fellatio (oral sex) with g-spot stimulation is enough to make most women become extremely excited.
For the super adventurous couple, (ie. already successful at locating the g-spot and comfortable with this technique). . . Be prepared to experience a totally new feeling. The partner, instead of using his/her index finger to locate the g-spot will now use their index finger and thumb to pull up some tissue from the vaginal walls and rub it between her/his finger and thumb. Before doing this, practice this technique by VERY LIGHTLY pinching some skin together. This is what you are doing with the vaginal wall. To do this, you must be EXTREMELY soft and gentle. The vaginal walls are extremely sensitive. It is better to err on too soft than too hard. Most women will never have felt this sensation before. This is something just different feeling. There is no other way to describe it. As you touch her vaginal walls, always give her two different forms of touch and ask her which one she likes better. Good luck.
check it out.. click on the link to see video demo
How To Locate, Find, & Stimulate The Female Gspot