try this,,,,:)
<asp:content id="Content1" contentplaceholderid="HeadContent" runat="Server" xmlns:asp="#unknown">
</asp:content>
<asp:content id="Content2" contentplaceholderid="MainContent" runat="Server" xmlns:asp="#unknown">
<asp:scriptmanager id="sm1" runat="server" />
<script type="text/javascript" language="javascript">
function uploadError(sender, args) {
alert(args.get_errorMessage());
document.getElementById('<%=lblStatus.ClientID%>').innerText = args.get_fileName(), "<span style="color:red;">" + args.get_errorMessage() + "</span>";
}
function StartUpload(sender,args) {
document.getElementById('<%=lblStatus.ClientID%>').innerText = 'Uploading...';
}
function UploadComplete(sender,args) {
var filename = args.get_fileName();
var contentType = args.get_contentType();
var text = "" + filename + " | " + args.get_length() + " bytes";
document.getElementById('<%=lblStatus.ClientID%>').innerText = text;
}
</script>
<div>
<ajaxtoolkit:asyncfileupload id="AsyncFileUpload1" width="400px" runat="server" xmlns:ajaxtoolkit="#unknown">
OnClientUploadError="uploadError"
OnClientUploadStarted="StartUpload"
OnClientUploadComplete="UploadComplete"
CompleteBackColor="Lime" UploaderStyle="Modern"
ErrorBackColor="Red" ClientIDMode="AutoID"
ThrobberID="Throbber"
UploadingBackColor="#66CCFF"
onuploadedcomplete="AsyncFileUpload1_UploadedComplete" />
<asp:label id="Throbber" runat="server">
<img src="Images/indicator.gif" align="absmiddle" alt="loading" />
</asp:label>
<br />
<asp:button id="Button1" runat="server" text="Start Upload">
onclick="Button1_Click" />
<br />
<br />
<asp:label id="lblStatus" runat="server" style="font-family: Arial; font-size: small;"></asp:label>
</asp:button></ajaxtoolkit:asyncfileupload></div>
</asp:content>
protected void AsyncFileUpload1_UploadedComplete(object sender, AjaxControlToolkit.AsyncFileUploadEventArgs e)
{
if (AsyncFileUpload1.HasFile)
{
string strPath = MapPath("~/NewsImages/") + Path.GetFileName(e.filename);
AsyncFileUpload1.SaveAs(strPath);
label1.Text=strPath;
}
}