Use the Table tab in the Table Properties dialog box to set table width.
Use the Table Properties box to quickly resize the table to a specific measurement or a specific percentage of the page. To access Table Properties, click the Layout tab and click Properties from the Table group.
Note If you're trying to resize a table to fit its contents or to fit the page, try the AutoFit options — explained in "Tables I: Get acquainted with tables."
On the Table tab, select the Preferred width check box and then enter the width you want. In the Measure in box, select either your default unit of measurement (such as inches or millimeters, set in Word Options) or Percent if you want the width to be a percentage of the entire table.
By default, tables are aligned against the left margin of the page. Tables can also be indented from left, centered, or right-aligned on the page.
From the Table tab, you can also adjust whether text wraps around the table, change the table's cell default margins, or access the Borders and Shading box. You'll hear more about the Borders and Shading box soon.