All of it depends on your interest and the course cut-offs of the IITs. You have to decide which course you're interested in, and then set a preference list according to the course and college that you want. You have got a good rank, so you will hopefully get a good IIT with a stream of your choice. You have to apply through JoSAA counseling and enter the preference list there. You will be allotted the course and college at the top, according to the cut-off of the college and the course. All the best, hope you get clear about what you want, and enjoy the course that you choose.