Hello govind if you get your respective branch in NIT Manipur then good for you and you can work hard along with first year of college as there are no special subjects in first year and give JEE again next year but you will have to start in the new college with first year again remeber that . i am providing you a link that will help you in predicting college and branch according to your rank https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer

and here is the link to show you in how much level you are

i am also providing you a link to check the cutoffs for all the NIT's i hope you find the one you like https://engineering.careers360.com/articles/jee-main-cutoff-for-top-nits

Stay safe