You can get admitted in IIT through Joint Entrance Exam (JEE). To learn more about IIT, Bombay go to
http://www.iitb.ac.in/ . To learn more about IITs in general go to
http://en.wikipedia.org/wiki/Indian_..._of_Technology .
You didn't mention if you want to go for a Post Graduation or you want to repeat your graduation in a more reputed college.
Admission in most reputed Government colleges in Maharashtra takes place through CEE.