Actually, if you want to get technical about it. The G-spot is located inside the front wall of the vagina. You can find the female g spot location halfway between the back of the pubic bone and the front of the cervix, along the course of the urethra and the bladder where it connects with the urethra. The size and exact location will vary slightly with each woman.
For some women hitting the g spot can bring deep and intense orgasms that differ from a clitoral orgasm. For other women stimulating the spot just makes them feel like they have to pee.
G-Spot orgasms are triggered by a brief, vigorous, application of rhythmical friction. The desired friction is usually achieved when intercourse is practiced from behind or in the doggy style sex position. Locate the G-Spot with your finger, the G-Spot will feel like a small bean, and when properly stimulated, may swell to the size of a dime or even as large as a quarter. Some women have large spots, just as some women have large breasts, and some men have large penises.
Here is a diagram of where it is and how to find it.