Dear anurag Aryan 

The first step for getting admission in IIT is about scoring good marks in JEE 

If you can score a good score in JEE main and advance you will get admitted in any of the iites 

JEE main is the step for JEE advance.The eligibility for advance depends on JEE main marks 

JEE advance cut off changes every year and it is usually around 35% of the total marks 

Best of luck