Help: IFFK Ticket Booking Process

Can someone please explain how the ticket booking system works for IFFK? This is my first time attending. Do you need to book tickets one day in advance? When will the bookings open? Is it free? How can I book tickets for the first-day films? Also, does the Nishagandhi venue require booking, or is it on a first-come, first-serve basis? Thanks for the help.