Hello Rahul,
NEET 2019 application forms will be released on November 1, 2018 by National Testing Agency (NTA), the exam conducting body. 
Application forms will release in online mode.
So, if you are asking about the Category details, then must fill the category to which you belong. You belong to OBC category so in the Category field you will have to select OBC.
It is suggested that you should fill all the details correctly and  carefully.
Also, admission to all the medical colleges will be on the basis of NEET UG score so you will have to register for NEET exam. And, choices for selecting the colleges will be available after the exam. As of now, you will  just have to register for the NEET exam.
You can aks if you have any other query.
Good Luck!