var printscreen = new Bitmap(
                Screen.PrimaryScreen.Bounds.Width,
                Screen.PrimaryScreen.Bounds.Height
            );

            var graphics = Graphics.FromImage(printscreen as Image);
            graphics.CopyFromScreen(0, 0, 0, 0, printscreen.Size, CopyPixelOperation.SourceCopy);

            printscreen.Save("screenshot.png", ImageFormat.Png);