The most important part of trying to make any girl squirt is foreplay- and lots of it! Foreplay for women is very important in getting them wet and ready to engage in any sexual actions. If you really would like to get your girl to squirt make sure she is comfortable first. If this is her first time then a bed is a great place to lay and relax as you attempt this. Giving her a pillow underneath her will not only help her be comfortable but will allow you more room and access to do what you need to. Making your girl squirt is not hard once you get down the basics.
Remember two things when attempting this: Comfort is a must for her and her G-spot plays the most important role in making her squirt.
Now to get on with the actual actions. The clitoris, as with most foreplay, is the place you want to start, rubbing slowly over the area to lubricate her vagina. Gradually increase the speed you are rubbing at and the pressure. When she is properly wet it is time to slip your finger into her and begin fingering her. The wall at the top of the vagina is the best place to focus your attention. Take your pointer and middle finger and use that to rub the inside of her vagina. You will need to find her G-spot, which when found should cause your girl to moan. It is usually found on the top wall of her vagina. Rub her G-spot, increasing pressure as you go, while your thumb rubs the clitoris. Increasing pressure and speed during this will cause a large build up. The girl needs to stay relaxed. This build up is something many girls stop because they think it is pee. It is actually a build up of orgasm fluids that when released will cause squirting.
There are so many sex positions that help to cause a girl to squirt. There is a type of missionary that causes your penis to rub against her G-spot. You must be on top however you must enter at an angle where you are on your knees. The girl then raises herself up to make her vagina level with your penis. She can then wrap her legs around your body and you will lightly thrust causing your penis to rub up against her G-spot. Do not thrust all the way however or you may not hit it. Another position is set up the same way as this one except her legs will be straight up in the air on your shoulders. This gives you much more room to access her vagina and when hitting the right spot can cause her to squirt.
After all this, remember that after a girl squirts she will usually require a resting period as squirting may causes vaginal sensitivity and may cause her to be in pain if you continue. Be gentle and always ask for consent before engaging in sexual activity or continuing after making her squirt.