the following two will give you screen height and width!!
place them just after the first // i guess!!
UINT windowStyle; DWORD extendedWindowStyle; int screenWidth = GetSystemMetrics(SM_CXSCREEN); int screenHeight = GetSystemMetrics(SM_CYSCREEN); int screenBpp = 16; //or any bits per pixel value you prefer
that will clear the first 5 errors, the problem is simply that you are not declaring your variables!!!
As for the last error, that involves looking properly and i dont have time, sorry!!