If you want to understand the details of the Olympiad route, please check out the wiki for Olympiads in India. In particular, the page on the path to the IMO should give you a rough idea of the route.
If you have some questions regarding the Olympiads, check out my compilation of Frequenty Asked Questions on Olympiads. This file contains questions on Olympiads that I have been asked in the past along with my considered responses. The responses are a mix of fact and my personal opinion.
In case you have further questions, feel free to mail me at vipul at cmi.ac.inReturn to Math Olympiad main page.