umm... this might be a kinda hard question, I dunno.

I have a picture right?

Code:
HBITMAP		hBitmapBackground;
HBRUSH		hBrush;

hBitmapBackground = LoadBitmap(hInstance, MAKEINTRESOURCE(IDB_MAIN));
hBrush = CreatePatternBrush(hBitmapBackground);
DeleteObject(hBitmapBackground);
And I'm about to set it to the background for my Window, but...
The picture isn't square. It's circular. How can I make it so, that everything in the picture that is the colour white, goes invisible??

So it reads each pixel in the picture, and if the pixel is white, then it just makes it invisible??