where we should type it

Answer 1

u can type it anywhere
even in notepad, mucrosoft word, etc

Answer 2

One of the basic compiler is Turbo C++. It is a software for typing codes and checking whether they are right or no. It also tells you where you have done a mistake. There are many more which you can get online.

Answer 3

use numbers below functional keys if you're using turbo c++