用CreateWindow()创建的主窗体如何添加背景图片

#include <windows.h>
  HDC hdc, hdcMem;
  HBITMAP hBmp;
  BITMAP bmp;
  HINSTANCE hCurInst;//当前应用程序句柄

hdc = BeginPaint(hWnd, &ps);;
hdcMem = CreateCompatibleDC(hdc);
SelectObject(hdc, (HPEN)GetStockObject(WHITE_PEN));
Rectangle(hdc, 0,0, 1000, 1000);
hBmp = LoadBitmap(hCurInst, MAKEINTRESOURCE(IDB_BITMAP1));
GetObject(hBmp, sizeof(BITMAP), (LPVOID)&bmp);//获取位图尺寸
SelectObject(hdcMem, hBmp);
BitBlt(GetDC(hWnd), 0, 0, bmp.bmWidth, bmp.bmHeight, hdcMem, 0, 0, SRCCOPY);
EndPaint(hWnd, &ps);