Question

how a FIR can be filled

Answer 1

by going to your nearby police station and giving them an account of the subject and reason on which you are filling fir and give a written report and your fir will be accepted and action will be taken soon ...

Answer 2

FIR Full Form is First Information Report
FIRs can be lodged by the person against whom the offence is committed, by the person who knows that the offence has been committed, or by the person who has seen the commissioning of an offence.