Any one know how to open text file ?

Question

I have this codes in my form: private void Open_Click(object sender, System.EventArgs e) { OpenFileDialog openFileDialog=new OpenFileDialog(); openFileDialog.Filter="Text(*.txt)|*.txt|Doc(*.doc)|*.doc " ; openFileDialog.ShowDialog(); } But this only reveal the open file dialog, when my menu item called Open is clicked.. How do I actually make the content of the selected file goes into one of my control, which is a RichTextBox.. I am just a beginner in C#, migrating from Java. Thanks