To find the G spot put you finger inside of her and make a beckoning motion and you should feel a change in the skin that is where the G spot is once you find it keep massaging it, it isn't like the clit so you can be a lot firmer. I find having sex to find the G spot it is easier if the women is on top, if your doing doggy style make sure she arches her back and if your on top then try to really push in with each thrust. I hope this should help.