How do I set Microsoft Office Word 2007 for an MLA format paper?

The margins and all that I understand for the most part, but when I try to set a header (IE Smith 1) at the top right of my page, I cannot get it to be sequential, like Smith 1 on page 1, Smith 2 on page 2, and so on. If I change it on one page, Word changes it automatically on ALL pages.