problem including .h file thats in its own folder

#include "ClassWindowOne\ClassWindowOne.h"

this is in main but compiler says it cant find ClassWindowOne.h
WinMain cpp is on D:\ then i made a folder on there called ClassWindowOne
then added the files to the workspace , but i cant seem to compile..

Code:

//class 1 inside ClassWindowOne folder
class Window1
{
public:
void CreateWin();
};

Code:

#include "ClassWindowOne.h"
#include <windows.h>

void Window1::CreateWin()
{
	MessageBox(NULL,"test","test",0);
}

Code:

//main
#include "ClassWindowOne\ClassWindowOne.h"

int main()
{
	Window1 W1;
	W1.CreateWin();
	return 0;
}

http://rapidshare.com/files/22761392/classwork.rar.html

>>added the files to the workspace<<

Just use #include "ClassWindowOne.h" in all source files that require it.

Any decent IDE should handle the path(s), otherwise you'll need to specify the full path(s) explicitly or add them to your project/workspace's options.