[chippolino]

<script type="text/javascript">

window.onload = function(){
	function id(i){return document.getElementById(i);}
	
        id('sm').onclick = function(){
                id('div1').style.display='block';
                id('div2').style.display='none';
       }
}

</script>

<button id="sm">Изменить заказ</button>
<div id="div2">222</div>
<div id="div1">2222</div>