How To Load File Into RichTextBox?

It Will Load Your Seelected File From The OpenDialogBox & Display Content Of That File Into the RichTextBox...

'On The Load Button's Click Event...

Private Sub btnLoad_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLoad.Click
        If OpenFileDialog1.ShowDialog = DialogResult.OK Then
            filename = OpenFileDialog1.FileName
            RichTextBox1.LoadFile(filename)
        End If
End Sub