Help with compiling?

1>------ Build started: Project: firsttutorial, Configuration: Debug Win32 ------
1>Compiling...
1>firsttutorial.cpp
1>c:\users\anthony\documents\visual studio 2008\projects\firsttutorial\firsttutorial\firsttutorial.cpp(10) : error C2065: 'cout' : undeclared identifier
1>Build log was saved at "file://c:\Users\Anthony\Documents\Visual Studio 2008\Projects\firsttutorial\firsttutorial\Debug\BuildLog.htm"
1>firsttutorial - 1 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

using namespace std

// firsttutorial.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"

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

#include <iostream>
using namespace std;
int main() {
 cout; <<"Hello World n";
 system("pause");
}

#include <iostream>

using namespace std;

int main(){

cout<<"Hello World!"<<endl;

system("pause");

return;}