'Handles the Enter key being pressed while TextBox1 has focus. 
Private Sub TextBox1_KeyDown(ByVal sender As Object, _
    ByVal e As KeyEventArgs) Handles TextBox1.KeyDown
    TextBox1.HideSelection = False
    If e.KeyCode = Keys.Enter Then
        e.Handled = True

        ' Copy the text from TextBox1 to RichTextBox1, add a CRLF after 
        ' the copied text, and keep the caret in view.
        RichTextBox1.SelectedText = TextBox1.Text + _
            Microsoft.VisualBasic.vbCrLf
        RichTextBox1.ScrollToCaret()
    End If
End Sub

    //Handles the Enter key being pressed while TextBox1 has focus. 
    private void TextBox1_KeyDown(object sender, KeyEventArgs e)
    {
        TextBox1.HideSelection = false;
        if (e.KeyCode==Keys.Enter)
        {
            e.Handled = true;

            // Copy the text from TextBox1 to RichTextBox1, add a CRLF after 
            // the copied text, and keep the caret in view.
            RichTextBox1.SelectedText = TextBox1.Text + "\r\n";
            RichTextBox1.ScrollToCaret();
        }
    }

private:
   //Handles the Enter key being pressed while TextBox1 has focus. 
   void TextBox1_KeyDown( Object^ /*sender*/, KeyEventArgs^ e )
   {
      TextBox1->HideSelection = false;
      if ( e->KeyCode == Keys::Enter )
      {
         e->Handled = true;

         // Copy the text from TextBox1 to RichTextBox1, add a CRLF after 
         // the copied text, and keep the caret in view.
         RichTextBox1->SelectedText = String::Concat( TextBox1->Text, "\r\n" );
         RichTextBox1->ScrollToCaret();
      }
   }

The following code example demonstrates how use the Keys enumeration and the TextBoxBase.ScrollToCaret method. To run the example, paste the following code
in a form containing a TextBox control called TextBox1 and a RichTextBox control called RichTextBox1. This example assumes the event-handling method has been associated with the KeyDown event.