Writing an on click event for a run time created button

Hi guys

I have a place holder and 2 run time created text boxes and a button in it. I want to write an onclick event for the button and there I need to have access to the run time created text box value to for example put it in another text box on the page. I googled and found I should write the event handler for the button like this:
TextBox newMessageSender = new TextBox();
PlaceHolder2.Controls.Add(newMessageSender);

 
Button messageBtn = new Button();messageBtn.Text = "Send ...