Hello Bruce, and thanks for your question.
The only ways to successfully trace your genuine ancestry is with help from a reputable site or organization (perhaps Ancestry.com or Genealogy.com), and asking relatives about your background/family tree. If your father said you are Native American, ask him for more details, and speak to other relatives, too. Write down all the information you find out and try to get first and last names (maiden names of mother, grandmother, great-grandmother, etc.), dates of birth and places of birth of relatives on both your parents' sides, if possible. Also ask your father the name of the Tribe you belong to, and this should help you locate more information, if you go directly to the people in charge of family records for your Tribe.
There are private geneaologists also, who can be hired to trace your family tree for you, if you supply enough (and accurate) information, and they do charge a fee.
I don't think the online sites that are free, will be of much help or go into any depth.
I think you'll find this information helpful:http://www.ehow.com/how_5903280_determine-ethnic-origins.html
I wish you the best of luck, and hope you are able to find out about your family history!
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Edited by Cher on 5/26/2010 at 1:47 AM EST