How do you know where your g spot is and how can you tell your touching it?

It's inside vagina. The "graffenburg spot" or "g" spot is in the upper portion of the vagina just in front of the cervix and under the bladder. It forms during 2nd stage female sexual excitement as a firm "tented" spot. It can be felt during that stage by placing a finger inside the vagina and making a "come hither movement" with that finger. It provides pleasure in additon to the clitoris.
The clitoris. The clitoris is what matters. This is the female pleasure center and the area that causes female orgasm.