Seiyuu say me

A seiyuu is a voice actor - somone who provides character voices for anime. I just found this out. I also just found out that the seiyuu for the character of Uzumaki Naruto is a woman: Takeuchi Junko. Of course, there's nothing wrong with this, I'm just incredibly surprised. Like way back when I found out Nancy Cartwright was the voice of Bart Simpson. How do they make these sounds?