I JUST SQUIRTED FOR THE FIRST TIME EVER!!!!!

EDIT: hahahah you guys are great okay uh, well I guess he just fingered me for a while and when it started building up, I asked him to go faster (like, really fast) (like really really fast, he was pounding that pussy) and as it keeps building up you feel that tension in your stomach like you have to pee and you kinda just have to push, just let it go like your peeing. But GIRL it's not pee lol trust me it's something else probably some kinda sex fluid sent from the heavens so that you can further claim your man's soul :) I hope this is kind of helpful it's really all about just finding what feels good and then focus on that feeling and letting your body go.

EDIT AGAIN: also try to position yourself in a way so that when he's fingering you he hits your gspot (if his fingers aren't long enough this may be hard, maybe his dick will help idk) (also if you don't know what a gspot is just keep trying different things until you feel it. Trust me you'll know when you do). Sometimes it's easier for him to reach it if I tip my hips up and he pushes his wrist down and fingers up (like aiming towards the upper wall of my vagina towards my stomach) but everyone's different so just keep trying it took my forever and when it finally happened it was magical!!!