It's really easy. I used to do this to my roomate all the time. Simply put your middle and ring fingers about an inch or two inside and play with your g-spot. You need to rub it and tap it in an upward motion. When you start getting off really start to pound it and you will lose all control. Every girl is different; some get off easier than others. It helps a lot of girls to have foreplay and a clitoral orgasm or two before squirting play. Have fun!