how to create an custom grammer file in C# for speech Recognition project

See more:

C#

I have following code for creating an grammer file ... but have some problem

code as follows

private SpeechRecognitionEngine rec = new SpeechRecognitionEngine();
rec.SetInputToDefaultAudioDevice();
string [] s={"My Computer","My Document","C Drive"};
grammerbuilder gb=new grammerBuilder();
gb.Append(s);
 rec.LoadGrammar(gb);
 rec.SpeechRecognized += new EventHandler<SpeechRecognizedEventArgs>(rec_SpeechRecognized);
rec.RecognizeAsync(RecognizeMode.Multiple);
                //RecognizedPhrase wordes = new RecognizedPhrase();
         
// this is an event method
void rec_SpeechRecognized(object sender, SpeechRecognizedEventArgs e)
        {
                    foreach (RecognizedWordUnit word in e.Result.Words)
            {

                   strdata = strdata +"  "+ word.Text;
            }
            textBox1.Text = strdata;

please see the above code by running it and solve my problem...
give me reply as soon as possible...
i am waiting for you...