Hey there

It depends on what branch of engineering you are interested in. It is very good to hear that you are sure about your career. Now for engineering you have to give JEE mains and if passed the cuttoff then advanced. According to the ranks you get in these exams you will get chance to get into iits or nits. Also you can get admission into iist as per your JEE advanced rank. Also there are other exams you can give for various private and state government colleges like bits Pilani, Jadavpur University etc.

Good luck