#include

#include

void main()

{

         cout << "Welcome to C++";

}

#include is used to command the compiler to use the file "iostream.h"

iostream.h is a header file which is already installed inside the compiler. iostream.h is needed inside the program above, because the block ( marked by "{" and "}" ) uses cout.  

cout itself is used to out: Welcome to C++ on the screen as the standard output of C++ compiler.