We need to build an application that record our desktop.We draw lines on desktop to notify the user that we are recording his/her desktop.We want to erase the lines after recording complete.We draw the lines using Graphics in C#.net.Please check the code below,   

```
IntPtr desktop = GetDC(IntPtr.Zero);
using (Graphics g1 = Graphics.FromHdc(desktop))
 {
   Pen blackPen = new Pen(Color.Orange, 10); 
   Point pleftTop = new Point(2, 1);
   Point pleftBottom = new Point(2, 765);
   g1.DrawLine(blackPen, pleftTop, pleftBottom); 
   Point pTopLeft = new Point(1, 3);
   Point pTopRight = new Point(1356, 3);
   g1.DrawLine(blackPen, pTopLeft, pTopRight); 
   Point pRight1 = new Point(1356, 1356);
   Point pRight2 = new Point(1358, 1);
   g1.DrawLine(blackPen, pRight1, pRight2); 
   Point pBottom1 = new Point(1, 765);
   Point pBottom2 = new Point(1356, 765);
   g1.DrawLine(blackPen, pBottom1, pBottom2);

   string text = string.Empty;
   int screenHeight = Screen.GetWorkingArea(this).Height;
   int screenWidth = Screen.GetWorkingArea(this).Width;
   text = "Recording your screen & audio";
   int centerWidth = ((screenWidth / 3));
   int opacity = 255; 
   g1.PixelOffsetMode = PixelOffsetMode.HighQuality;
   g1.DrawString(text, new Font("Arial", 15), new SolidBrush(Color.FromArgb(opacity,    Color.WhiteSmoke)), centerWidth, 0);

```