How do I capture screenshot except my active form

void Button1Click(object sender, EventArgs e)
{
	Bitmap SS=Screenshot();
	pictureBox1.Image=SS;
	pictureBox1.SizeMode=PictureBoxSizeMode.Zoom;
}

private Bitmap Screenshot()
{
    this.Hide();
    Thread.Sleep(500);
    Bitmap screen = new Bitmap(SystemInformation.VirtualScreen.Width,
                                         SystemInformation.VirtualScreen.Height);
 
 
    Graphics g = Graphics.FromImage(screen);
 
 
    g.CopyFromScreen(SystemInformation.VirtualScreen.X,
                             SystemInformation.VirtualScreen.Y,
                             0, 0, screen.Size);
    g.Dispose();
 
    this.Show();
    return screen;
}