I have PCB and computer science in class 12 so I am able to do btech in that?
JEE Main is the National Level Exam for the admission to B.tech programme to get into NITs, IIITs, GFTIs. As per the eligibility you should have five subjects 1 -Language, 2 -Physics, 3 -Mathematics ( Compulsory ), 4 -Any one of (Chemistry, Biology, Biotechnology, Technical Vocational Subject), 5 -Any other subjects.
You should have minimum 75% in class 12th as a General Category & 65% as a reserved category or you should be in top 20 percentile in class 12th exam from the respective board.
You can also apply for the other University level like BITSAT, VITEEE, SRMJEEE or the state level Engineering Entrance Exam. As per the eligibility to apply, You should have passed in Physics, Chemistry and Mathematics in your 10+2.
Good Luck!