Hello, I hope you are asking about Bihar board exam for the academic year 2021 to 2022.The Bihar board has closed the applications for the academic year of 2020-2021. You should apply in next year in the month of September to October 2021.Check out the registration process of the 2020 year from this link https://school.careers360.com/exams/bihar-board-12th

Hope this helps, if not kindly specify your query.