I've met a guy who claims that he can make any girl squirt (and have seen proof
)...
I'm not exactly sure about the technical details but it does involve exciting the g-spot in such a way that causes the gland to forcefully excrete fluid. There's a lot of controversy about what's really in this fluid but it seems to be a combination of vaginal fluid and sometime urine.
This may sound disgusting, but it really is a physical manipulation of the gland that causes you to squirt. It's not the same as an orgasm. While is it possible that some girls can do this in combination with an orgasm, it's possible to squirt without actually having an orgasm.
Don't get frustrated if you're not able to do this! Sex is about your pleasure individually and as a couple - not how far (or if) you can squirt...