you dont need a spoiler the one mazda designed for the car works just fine for what its made to do. If your intrested in modding your car you should really do some research, asking basic questions like this will get you flamed as you can see. If your just intrested in doing looks for the car (i'm guessing you are cause you asked about a wing) you would want to probably check out mazdaspeed or some of the other mazda friendly companies, check out Corksport.com that will be a good start.

But as for actually modding your car, since you dont have that much knowledge i recomend not modding your car, you didn't pick an easy car to get started with.