First we start with a message box. This is going to be like the gui version of the C++ "Hello World" Program. I highly recommend buying sublime text to use and a mingw compilier. //api.cpp #include <Windows.h> int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR szCmdLine, int iCmdShow) { MessageBox(0,"Hello World","Hello World", MB_YESNOCANCEL | MB_ICONINFORMATION); } Now we add a reply function (a simple beep) #include <Windows.h> int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR szCmdLine, int iCmdShow) { int reply = MessageBox(0,"Hello World","Hello World", MB_YESNOCANCEL | MB_ICONINFORMATION); if(reply==IDYES){ while(1){ Beep(533,1000); } } }