How to implement WTSRegisterSessionNotification function

Question

I want to implement WTSRegisterSessionNotification function for my project and now I'm stuck with HINSTANCE hInstance;

I want an coding example how to implement HINSTANCE in c++

#include <windows.h>
#include <stdio.h>
#include <iostream>
#include <string>
#include "Wtsapi32.h"
#include <tchar.h>

#pragma comment( lib, "user32.lib" )

using namespace std;

static TCHAR szWindowClass[] = _T("win32app");
// The string that appears in the application's title bar.
static TCHAR szTitle[] = _T("Win32 Guided Tour Application");

void main()
{
    // Lock the workstation.
    HWND hWnd = CreateWindow(
        szWindowClass,
        szTitle,
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT,
        500, 100,
        NULL,
        NULL,
        GetModuleHandle(NULL),
        NULL
    );

    cout<< WTSRegisterSessionNotification(hWnd, NOTIFY_FOR_ALL_SESSIONS);;

    if (!LockWorkStation())
    {
        printf("LockWorkStation failed with %d\n", GetLastError());
    }

    cout << WTSRegisterSessionNotification(hWnd, NOTIFY_FOR_ALL_SESSIONS);;

    system("pause");
}

I want to implement WTSRegisterSessionNotification(hwnd, NOTIFY_FOR_ALL_SESSIONS);

I'm getting this error:

LNK2019 unresolved external symbol _WTSRegisterSessionNotification@8 referenced in function _main

and find out what values it returns