Fatal error for iostream

Question

I am attempting to learn c++ using the Code::Blocks application suggested for this course. The simple "Hello world" code below came built into the program and works fine.
#include <iostream>
using namespace std;
int main()
{
cout << "Hello world!" << endl;
return 0;
}
However, if I copy the same code into a different file and try to run it again, it says "fatal error: iostream: no such file or directory"
Is there something I need to download or add to the application or code to make this work?