Add text on Dynamic Data Display Map C#

Question

I am creating a wpf application that includes a Dynamic Data Display map chart in Visual Studio 2010. I have a Segment (line) on the chart. I want to add a text to this segment. I don't care where the text will be (on or under the line or in the side of) but I want to add a text to it, and don't succeed. If any one knows the property or TextBlock I need to add, I would be very happy. It should be running in no time. I need it in c# code not in xaml. My code to add the line:

       // Make the last line between the last point to the first point
        segmentHelper = new Segment(new Point(x1, y1),new Point(x2, y2));

       // Adding the line to the map - chartplotter
       plotter.Children.Add(segmentHelper);