JEE Main

Hi,
If you want to change your percentage then you should repeat class 12th and for JEE Main, you should join a decent coaching institute.

Just go to institution's website and fill the application form.

Try for bigger NIT's as you can get one. Though , these NIT's offer core branches at a very higher nice rankings , for yours you'll get mining and metallurgy in NIT surathkal , and similar in top three , below thaat you can try for good and core branches where you can expect CSE in MVNIT , VSNIT , our NIT rourkela.
You can check the previous year cutoff from these rank. For other colleges (NIT's ),
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor

Course fee in Chaitanya Bharathi Institute of Technology, [CBIT] Hyderabad is slightly high. It's around Rs. 1.13 lakhs per year for convenor and B category quotas (through EAMCET and JEE mains) and Rs. 3.25 lakhs for NRI sponsored quota.
For details regarding , go to
http://cbit.ac.in/files/cbitfee1.pdf

You have still many options left. Though you need to compromise a lot with these marks. A drop is something will take a one year but lend you some good options. Though ask yourself whether you can handle that pressure. Moreover, try for private universities or autonomous institutes. Try this also:
https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor

Let me answer you in a different way. Every institute will be good for you if you are ready for hard work. But personally based on the previous results I think that the educational giants such as Allen, resonance will provide you nourishing and competitive environment for JEE 2020
Hope it helps you.

Though, if the Advanced marks are this much, then you may get into one of the best government. Colleges in South India for aeronautical. No, NIT offers aeronautical engineering hence you can try for other cores with them.