You can report at the police station in whose jurisdiction the event has taken place either by phone or visiting personally. You can even send your written complaint by post. If you have complaint against a police officer, you can send or report the complaint to the SHO & D.S.P. and even to the higher authorities.
If your complaint does not disclose any offence or your complaint discloses only non-cognizable offence, then FIR cannot be registered. In such cases where only non-cognizable offence is made out, Police officer will enter the substance of information in the general diary of Police Station and give copy of same to complainant. Another copy of complaint is sent to the concerned judicial magistrate for further action. Police does not have powers to investigate a non-cognizable offence without the orders of the magistrate.