First of all, the onchange event is for the select element, not the option elements. Those don't actually change. Also, you have two JavaScript functions. showUser() and copy(). But you describe only one piece of functionality. What do these two functions do?
As for showing the text in the label, here's one way to do it (using jQuery, because everybody does):
$(document).ready(function() {
$('#users').change(function() {
$('#myLabel').text($(this).val());
});
});
What this is basically doing is:
change event of the specified select element.select.Try putting the onChange attribute in the select tag.
Example: http://jsfiddle.net/r6Fus/
HTML:
<div id="label"></div>
<select id="mySelect" onchange="copy();">
<option value="">Select a person:</option>
<option value="tcs" >tcs</option>
<option value="wipro" >wipro</option>
<option value="Hcl" >Hcl</option>
<option value="krystal kones" >krystal kones</option>
</select>
Javascript:
function copy() {
document.getElementById("label").innerHTML = document.getElementById("mySelect").value
}
Otherwise you could use jQuery.