I have found some helpful websites for you to research .
Some additional websites may help you understand this fascinating culture.
Writing the 12 animal Chinese characters
Chinese Zodiac legend
http://www.china-corner.com/article_list.asp?id=861
Chinese Zodiac
http://www.chinatoday.com/culture/zodiac/zodiac.htm
Chinese Astrology
http://en.wikipedia.org/wiki/Chinese_astrology
http://www.psychicguild.com/Chinese-Horoscope/
Chinese Calendar