Want to be come C.I.D. after 10+2
CID. is a Unit of state Police Force. You cannot get directly into C.I.D. and there are no courses for this. You will have to get job with the State police force first to be in CID later.
You can get a job in the State police force through IPS (Indian Police Service) cadre. You can also get jobs through MPSC (Maharashtra Public Service Commission) conducted examination for recruiting Maharashtra Civil Services officers. Police forces also recruit sub-inspectors through their own written test, interview and physical tests. For application, please look for advertisements in the leading newspapers in the State as well as Employment News.