About one third of women can “squirt” during orgasm. The fluid comes from her urethra and can vary in quantity depending on the woman. Squirting isn't something to fixate on, just like having an orgasm. So no pressure, it’ll come in time. Not all women experience squirting and some not until they are older. While others drown in it.
Depending on the woman’s anatomy, it might be easier to use fingers to stimulate her G-spot, other times a vibrator or dick. Some sexual positions that usually work well are the cowgirl or doggie style. Mostly because the woman has more control over the angle of insertion.
Want to read more? Then check out:
Cum Swapping,
Cum Swallowing,
Fingering Photos: Pixelio: Damm, Pipping