Or just....
DrawRectangle!
http://windowssdk.msdn.microsoft.com/en-us/library/ms534038(VS.80).aspxThe following code assumes you know how to include the GDI+ headers, are using the flat C API, can figure out how to check the status variable, and have the HDC as hDC, int variables x, y, width, and height, and ARGB values foreColor and backColor.
GpGraphics* gfx;
GpStatus status = GdipCreateFromHDC(hDC, &gfx);
// check status
// create line and fill brushes
GpSolidFill* foreBrush, fillBrush;
status = GdipCreateSolidFill(foreColor, &foreBrush);
// check status
status = GdipCreateSolidFill(backColor, &fillBrush);
// check status
// draw the fill
status = GdipFillRectangleI(gfx, fillBrush, x, y, width, height);
// check status
status = GdipDrawRectangleI(gfx, foreBrush, x, y, width, height);
// check status
I highly recommend learning GDI+. It is a very robust system, and very slick in .NET.