LPCTSTR lpClassName pointer to registered class name.
LPCTSTR lpWindowName pointer to window name.
DWORD dwStyle window style.
int x horizontal position of window
int y vertical position of window
int nWidth window width
int nHeight window height
HWND hWndParent handle to parent or owner window
HMENU hMenu handle to menu or child-window identifier
HANDLE hInstance handle to application instance
LPVOID lpParam pointer to window-creation data 
HWND CreateWindow
( LPCTSTR lpClassName,
  LPCTSTR lpWindowName,
  DWORD dwStyle,
  int x,
  int y,
  int nWidth,
  int nHeight,
  HWND hWndParent,
  HMENU hMenu,
  HANDLE hInstance,
  LPVOID lpParam
);

You should read the CreateWindow entry in - Microsoft® Win32® Programmer's Reference - for more detail.