Hello dear student,

As you said you want to do computer science engineering which is BTech in computer science and you want to learn coding. There are many online platforms available for you to learn it .

You must learn C language, C++ Atleast know the basics of these so that you don't have to face problem in understanding during the classes.

If you want to learn it for free then you try YouTube. There are really good channels from where you can start from scratch. While you can try different courses from udemy , and also from coursera.

I hope these are helpful

Thank you