How to Modify or Create a Theme in Word 2010
Word 2010 doesn't allow you to create your own themes from scratch, but you can modify existing themes to make your own, custom theme. You start by modifying existing theme colors and fonts:
To create a custom color theme: Choose Colors→Create New Theme Colors. Use the Create New Theme Colors dialog box to pick and choose which colors apply to text or various graphical elements in your document.
To create a custom font theme: Choose Fonts→Create New Theme Fonts. Use the Create New Theme Fonts dialog box to select your fonts — one for the headings and another for the body text.
To remove a custom theme: Right-click it on the Themes menu and choose the Delete command. Click the Yes button on the prompt that appears to remove the theme.
Regardless of which kind of theme you create, give the new theme a name and save it. You can then choose that theme from the Custom area of either the Colors or Fonts menu.
When you’re using a set of theme colors, fonts, and graphics styles — even if you didn’t create them yourself but merely used them to organize your document — you can collect the various elements as a theme: Choose Save Current Theme from the Theme menu and use the dialog box that appears to give your theme a proper descriptive name and save it. The theme you create then appears in the Custom area of the Themes menu.