First off. DO NOT SHAVE IT!!! never shave your face it will come in thicker and more course.
If its a small moustache just on the sides of your mouth you can try to tweeze the darkest hairs (thats what i do, i'm 16) its painful at first similar to your eyebrows but it gets easier with time.
Either that or if its pretty bad then just get a sensitive waxing kit, its simple to do your self. there are so many diffrent kinds out there, ones that have the wax already on the strips, ones that are quick, ones that are for sensitive skin. Just head down to your local shoppers and take you pick.
Hope that helps.