Microsoft Access - Set the value of a textbox based on the value of another textbox

<body> <h1><a rel="nofollow" href="http://www.techonthenet.com/access/textboxes/after_update.php" >Set the value of a textbox based on the value of another textbox</a></h1> <p>What VBA code do I use to set the value of a textbox based on the value of another textbox?</p> <p><a href="http://www.tutcity.com/">More Tutorials</a></p> </body>