ผมอยากทราบวิธีส่งค่าให้ ajax จาก listmenu 2อันครับ

<script language="JavaScript">
	   var HttPRequest = false;

	   function list_names(user) {
		  HttPRequest = false;
		  if (window.XMLHttpRequest) { // Mozilla, Safari,...
			 HttPRequest = new XMLHttpRequest();
			 if (HttPRequest.overrideMimeType) {
				HttPRequest.overrideMimeType('text/html');
			 }
		  } else if (window.ActiveXObject) { // IE
			 try {
				HttPRequest = new ActiveXObject("Msxml2.XMLHTTP");
			 } catch (e) {
				try {
				   HttPRequest = new ActiveXObject("Microsoft.XMLHTTP");
				} catch (e) {}
			 }
		  } 

		  if (!HttPRequest) {
			 alert('Cannot create XMLHTTP instance');
			 return false;
		  }
	
			var url = 'query_user.php';
			var pmeters = 'user='+user;
			HttPRequest.open('POST',url,true);

			HttPRequest.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
			HttPRequest.setRequestHeader("Content-length", pmeters.length);
			HttPRequest.setRequestHeader("Connection", "close");
			HttPRequest.send(pmeters);
			
			
			HttPRequest.onreadystatechange = function()
			{

				 if(HttPRequest.readyState == 3)  // Loading Request
				  {
				   document.getElementById("mySpan").innerHTML = "Now is Loading...";
				  }

				 if(HttPRequest.readyState == 4) // Return Request
				  {
				   document.getElementById("mySpan").innerHTML = HttPRequest.responseText;
				  }
				
			}

	   }
	</script>


User : 
<select name="userlist" id="userlist" onChange="list_names(this.value);">
<?php
	echo "<option value=\"all\" >All</option>";
    $sql = mysql_query("SELECT user FROM account");
	while($objResult = mysql_fetch_row($sql))
	{
		echo "<option value=\"$objResult[0]\" >$objResult[0]</option>";
	}
?>
</select>

Tool : 
<select name="typelist" id="typelist">
	<option value="all" >All</option>
    <option value="discoveringtool" >Motif Discovering Tool</option>
    <option value="assesment1" >Assesment Tool 1</option>
    <option value="assesment2" >Assesment Tool 2</option>
</select>