Use File | New to create a document from a template (applies to Word
97/2000/2002/2003). When you start Word, a blank document based on the
normal.dot template is created for you.

For more, see the following articles:

What do Templates and Add-ins store?
http://word.mvps.org/faqs/customization/WhatTemplatesStore.htm

Creating a Template - The Basics (Part I)
http://word.mvps.org/faqs/customization/CreateATemplatePart1.htm

Creating a Template (Part II)
http://word.mvps.org/faqs/customization/CreateATemplatePart2.htm

Tips for understanding Microsoft Word styles
http://www.shaunakelly.com/word/styles/TipsOnStyles.html