MS Word: Make headers different for odd and even pages in Word 2007

Select the Page Layout tab in the toolbar at the top of the screen. Then in the Page Setup group, click on the Page Setup Dialog Box launcher. This is the button in the bottom right corner of the Page Setup group.

When the Page Setup window appears, click on the Layout tab. Check the "Different odd and even" checkbox. Click on the OK button.

Now you can modify the header for even pages on an even page and odd pages on an odd page.