Speech Recognition

[C# Programming]

Hello,
I need to develop one application say, if i speak "run notepad", notepad should be opened.
For that i have use following code to implement speech recognition,
SpeechRecognitionEngine recognizer = new SpeechRecognitionEngine();
DictationGrammar gram = new DictationGrammar();
recognizer.LoadGrammar(gram);
recognizer.SetInputToDefaultAudioDevice();
recognizer.RecognizeAsync(RecognizeMode.Multiple);
void recognizer_SpeechRecognized(object sender, SpeechRecognizedEventArgs e)
{
MessageBox.Show(e.Result.Text);
}


I don't know how to add grammer, please help me out.
Thank you in advance.