First, Create a web page default.aspx and put the html code as following..
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<asp:ScriptManager ID="MainScriptManager" runat="server">     
</asp:ScriptManager>     
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Now, Create a usercontrol my first user control
Create a function called AddScriptReference as following...
'--------------------------------------------------------------------------    
private void AddScriptReference()     
{     
     ScriptManager scriptManger = ScriptManager.GetCurrent(this.Page);     
     if (scriptManger != null)     
     {     
         ServiceReference serviceReference = new ServiceReference();     
         serviceReference.Path="~/MyWebService.asmx";     
         serviceReference.InlineScript = false;  
         scriptManger.Services.Add(serviceReference);    
     }     
     else     
     {     
         throw new Exception("Script Manager Not Found");     
     }     
}     
'--------------------------------------------------------------------------     
Then override controls init event as following... 
'--------------------------------------------------------------------------    
protected override void OnInit(EventArgs e)     
{     
     AddScriptReference();     
     base.OnInit(e);     
}     
'-------------------------------------------------------------------------- 
