Hey Ankit,Yes you need to fill online application form to apply for admission in GGSIPU and the eligibility or the merit will be decided on the basis of marks you have obtained in JEE mains paper 1.

If u haven't checked the result go ahead and check it on the link below

https://www.google.com/amp/s/admission.aglasem.com/ipu-cet-result-btech-131/

All the best!! Hope it helps.