How to Use the Center Tab Stop in Word 2010
Word 2010's center tab is a unique critter, and it has a special purpose: Text placed at a center tab is centered on a line. You can use the center tab for header or footer information (which is about the only time you use the center tab stop).
Start a new paragraph, one containing text that you want to center.
Center tabs are found in one-line paragraphs.
If necessary, click the View Ruler button to display the Ruler.
The Ruler may be hidden.
Click the Tab gizmo until a center tab appears, and then click the mouse on the light gray part of the Ruler to set the tab.
For example, you can place the center tab at the center of the page, at the 3-inch position.
(Optional) Type some text to start the line.
The text you type should be short; it appears only at the start of the line.
Press the Tab key.
The insertion pointer hops over to the center tab stop.
Type the text to center.
While you type, the text is centered on the line. Don't type too much; remember that the center tab is a single-line thing.
Press Enter to end the line of text.
Obviously, if you just want to center text on a line, centering the entire paragraph is a better choice. This technique finds itself used mostly in page headers and footers.