My girl friend and I live together and natrually have sex and I am able to make her cum by stimulating her clitirous but i can not find her G-spot and she cannot either. We are very open with each other and are totally comfortable with each other.
You either don't know where to feel or
you are feeling it and neither of you know it
or she has one that is not particularly responsive.
Few women can feel it themself. ( I never have.)
The other person inserts fingers, curls them around pubic bone, feel for a section that feels rougher, and rubs. It is the size of quarter/pound. It gets spongier/larger when excited.