How do you spell your surname?

你的姓怎么拼？

How do you spell "potato?"

“”怎么拼写？

Well, how do you spell your family name in English?

喔，你的姓用英语怎么拼写？

Susan: How do you spell that?

苏珊：盖尔品怎么拼？

And how do you spell your name?

你的名字怎么拼？