USCIS stands for the United States Citizenship and Immigration Services. This is the part of the U.S. government that deals with people who would like to become U.S. Citizens. As of 2013, the nearest USCIS office that gives the Naturalization (Citizenship) Exam is located at 301 Roycroft Drive, Durham, NC 27703.
This is the USCIS website on citizenship. It has many resources, including study guides to help you prepare for the exam: http://www.uscis.gov/citizenship