What is the procedure for admission in iiit any seperate form to be filledup.

It depends on the type of IIIT. Government and private follow separate procedure. Check on the website of the individual coege for due admission procedure.

In government and public-private partnership IIIT, admission is through JEE Mains. For private IIIT, like IIIT Hyderabad, IIIT Bangalore, etc. You have to fill a separate form that will be available on their respective official website.

https://www.shiksha.com/college/iiit-allahabad-indian-institute-of-information-technology-iiita-26486/admission.