You may file a written complaint and mail it to:
Federal Communications Commission
Consumer & Governmental Affairs Bureau
Consumer Inquiries and Complaints Division
445 12th St., SW
Washington, DC 20554
You can file a complaint on-line  , using the FCC Complaint form 475B.
The Commission asks complainants to provide the following information: (1) the date and time of the alleged broadcast; (2) the call sign or the frequency of the station involved; and (3) the name of the program, the DJ personality, and the city and state; (4) information regarding the details of what was actually said (or depicted) during the alleged indecent or obscene broadcast. With respect to item (4), in making indecency determinations, context is key! The Commission staff must have sufficient information regarding what was actually said during the alleged broadcast, the meaning of what was said and the context in which it was stated. There is flexibility in how a complainant may provide this information. For example, the complainant may provide a significant excerpt of the program describing what was actually said (or depicted) or a full or partial tape or transcript of the material. In whatever form, the complainant provides the information, it must be sufficiently detailed such that the Commission can determine the words and language actually used during the broadcast and the context of those words or language. More information about obscenity and indecency complaints.