Dear aspirant,

The engineering stream you choose depends upon your marks and the college and the stream. You don't have to study any topics of engineering in your preparation of jee exam. All you have to study is physics chemistry and mathematics of 11th and 12th and that too according to the syllabus of JEE main exam.

After that you have to give the exam and when you get your result and rank then you will go for the online counselling. In counselling you have to fill the branch and the college choices according to your preference. Then a seat is allocated to you on the basis of your rank if you have a good rank then you will get the topmost choice you are selected and so does if you have loading you will not be able to get your top top preference.

Right now for 11th you have to study all the topics which are important for the JEE main exam and the same you have to do for your 12th in try to secure a good rank. t

thesyllabus of JEE exam:

https://www.google.com/amp/s/engineering.careers360.com/articles/jee-main-syllabus/amp