For many types of discrimination (race, color, disability, age, national origin, gender or sexual harassment) an employee must file a claim with the U.S. Equal Employment Opportunity Commission (EEOC).
The EEOC is a Federal Agency of the U.S. Government that will investigate your claim of discrimination. Once the EEOC completes the investigation they will usually issue a right to sue letter which gives you the right to file a lawsuit. There are strict time limits so you should seek an attorney immediately. Also, most EEOC “right to sue letters” give you 90 days to file a suit. Even if you are after the 90 days you should seek an attorney because an attorney may be able to help you even if you are past the 90 day deadline.