I am facing a lot of problems studying Computer Science (C++) in my school. My fellow class mates say that it will be must for me to study C++ in my first year in any Engineering College. Please tell me about its importance in my future and how is it going to affect my marks in colleges?

In some colleges, it is a compulsory subject in all branches, whereas in others, it is just an additional subject to which grades are awarded and not marks. Branches like Computer Science, IT, EC have a great deal of linkage to programming language C++. Other branches like mechanical, etc. also have programming applications in their curriculum (MATLAB) which is more or less based on the principles of C and C++.
C++ or any coding language knowledge will take you a step ahead in college, be it any branch because of the simulations and techniques that are nowadays used.It does not affect much the percentage but if you have learnt it before entering college, it acts a great advantage to you to get into and excal in any field of your choice.