ขอคำแหนะนำหน่อยครับ เกี่ยวกับ การ upload file นะครับ

<table>
<tr><td>Email:</td><td><input type="text" name="hc4bf" id="hc4bf" value="<? echo"$hc4bf"?>"  disabled='true' /></td></tr>
<tr><td></td><td><input type="checkbox" name="chkCon"  value="1" id="chkCon" onClick="check(this)" /><font color="#999999" size="2"> คุณต้องการปรับปรุงข้อมูล</font></td></tr>
<tr><td></td><td><input id="fileupload" name="fileupload" type="file" id="fileupload" disabled="true" ></td>
<tr><td></td><td><input name="btn" id="btn" type="button"  value="ปรับปรุงการแก้ไข" OnClick="JavaScript:doCallAjax('UPDATE'); " disabled='true'/></td></tr>

<?
}
?>
<table>

 var HttPRequest = false;

	   function doCallAjax(Mode) {
		  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 = 'update_site.php';
		  var pmeters = "thff07=" + encodeURI( document.getElementById("hff07").value) +
						"&th6b9e=" + encodeURI( document.getElementById("h6b9e").value ) +
						"&th07f5=" + encodeURI( document.getElementById("h07f5").value ) +
						"&thb50a=" + encodeURI( document.getElementById("hb50a").value ) +
						"&th7964=" + encodeURI( document.getElementById("h7964").value ) +
						"&thfca5=" + encodeURI( document.getElementById("hfca5").value ) +
						"&thf011=" + encodeURI( document.getElementById("hf011").value ) +
						"&th3248=" + encodeURI( document.getElementById("h3248").value ) +
						"&th44c0=" + encodeURI( document.getElementById("h44c0").value ) +
						"&th7660=" + encodeURI( document.getElementById("h7660").value ) +
						"&thc4bf=" + encodeURI( document.getElementById("hc4bf").value ) +
						"&fileupload=" + encodeURI( document.getElementById("fileupload").value ) + //ตรงนี้คือตัวแปรที่ผม get ขึ้นมาใช้นะครับ
						"&id3=" + encodeURI( document.getElementById("id3").value ) +
						"&tMode=" + Mode;





			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...";
				  }

				
				
			}

	   }