Ancestry.com is a fee-based** genealogical organization in the United States that provides access to genealogical and historical records from the United States and the World. You can start building your family tree with information you know and it will provide hints/suggestions of records that might be about that person to help guide your research.
Check with your local public library to see if they provide access to Ancestry through their electronic resources. For those in Northern Virginia, Arlington Public Library, Fairfax County Library, and Alexandria Library all provide access to Ancestry Library Edition.
**While a 14-day free trial is available, you are required to enter credit card information when you register, so if you decide to use Ancestry.com please be aware of this and monitor your trial unless you would like a membership.