For people that do not know GUI Stands for Graphics User Interface and it is what make the program look like a actual program and not a console application that every one of my programs are in (The CMD Prompt screen)

Here is a picture of the program:



Here is the code:

Code:
#include <windows.h>

const char g_szClassName[] = "myWindowClass";

LRESULT CALLBACK WndProc (HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch (msg)
    {
        case WM_CLOSE:
        DestroyWindow(hwnd);
        break;
        case WM_DESTROY:
        PostQuitMessage(0);
        break;
        default:
        return DefWindowProc (hwnd, msg, wParam, lParam);
    }
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    WNDCLASSEX wc;
    HWND hwnd;
    MSG Msg;

    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = 0;
    wc.lpfnWndProc = WndProc;
    wc.cbClsExtra = 0;
    wc.cbWndExtra = 0;
    wc.hInstance = hInstance;
    wc.hIcon = LoadIcon (NULL, IDI_APPLICATION);
    wc.hCursor = LoadCursor (NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH) (COLOR_WINDOW+1);
    wc.lpszMenuName = NULL;
    wc.lpszClassName = g_szClassName;
    wc.hIconSm = LoadIcon (NULL, IDI_APPLICATION);

    if (!RegisterClassEx(&wc))
    {
        MessageBox (NULL, "Windows Registration Failed", "Error", MB_ICONEXCLAMATION | MB_OK);
    }

    hwnd = CreateWindowEx(WS_EX_CLIENTEDGE, g_szClassName, "Win32 Practice", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, 2000, 2000, NULL, NULL, hInstance, NULL);

    if (hwnd == NULL)
    {
        MessageBox (NULL, "Windows Creation Failed", "Error", MB_ICONEXCLAMATION | MB_OK);
    }

    ShowWindow (hwnd, nCmdShow);
    while (GetMessage (&Msg, NULL, 0, 0) > 0)
    {
        TranslateMessage (&Msg);
        DispatchMessage (&Msg);
    }
    return Msg.wParam;
}
I used a tutorial for this and I don't fully understand it but I am slowly but surely getting it.