Muskan, first of all you need to appear for JEE-Main exam than after qualifying this you have to appear for JEE-Advance exam. If you get good marks in JEE-Advance than you will be eligible for admission to IITs.

Note that you also have to score 75% or more in your board exams or you should be in top 20 percentile of your board merit list.

I hope this answer helps you.

Good Luck!!