Какие должны быть знания для перехода на приложения с GUI?

#include <windows.h>
LONG WINAPI WndProc(HWND, UINT, WPARAM,LPARAM);
 
int WINAPI WinMain(HINSTANCE hInstance,
                   HINSTANCE hPrevInstance,
                   LPSTR     lpCmdLine,
                   int       nCmdShow)
{
    HWND hwnd;
    MSG msg;
    WNDCLASS w;
    memset(&w,0,sizeof(WNDCLASS));
    w.style = CS_HREDRAW | CS_VREDRAW;
    w.lpfnWndProc = WndProc;
    w.hInstance = hInstance;
    w.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
    w.lpszClassName = "WindowClass";
    RegisterClass(&w);
    hwnd = CreateWindow("My Class", "Window", WS_OVERLAPPEDWINDOW,
        300, 200, 200, 180, NULL, NULL, hInstance, NULL);
    ShowWindow(hwnd,nCmdShow);
    UpdateWindow(hwnd);
    while(GetMessage(&msg,NULL,0,0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
}
 
LONG WINAPI WndProc(HWND hwnd, UINT Message, WPARAM wparam, LPARAM lparam)
{
    switch (Message){
    case WM_DESTROY: 
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hwnd, Message, wparam, lparam);
    }
    return 0;
}