There are plenty of websites that offer support for using styles in Word. Most of the information applies to all versions of word. Here are a couple to get you started:

http://www.addbalance.com/usersguide/styles.htm
http://shaunakelly.com/word/styles/tipsonstyles.html

Both of these websites offer much more that what you are asking but, will help you ten-fold for future assistance.

Hope this helps...