Here is my code:

#include <iostream>
using namespace std;

int main () {
    cout << "Hello World";
    return 0;
}

And when I try to run it, it shows this:

g++ : The term 'g++' is not recognized as the name of a cmdlet, function, script file, or operable program.

Can anyone tell me what I did wrong? Or is there a way to fix this?