I'm an NW25 in MAC world and i use the shade 4 light in the dream matte mousse. So since you're lighter than me, you might be a 2 or 3. Maybe even 4. The best thing to do would be to go the drugstore and try some of the testers they have out. Good luck :)
ew i don't think dream matte mousse even compares to mac but i really don't like cream or liquid foundations.
i'm NW20 and i use I use mineralize skin finish natural - medium as my everyday "foundation." medium dark in the summer/contour i highly recommend it if you just like light coverage.
Go into a CVS most of the time they will have skin tone samplers to help you choose your shade...
go in the store and start sampling! You've had your face probably all your life haven't you? I would say you could just about look without even trying it! I can anyway