ajax control toolkit 3.5 how to set up

Hi:

I have a problem on how to set up ajax control toolkit 3.5 ; My project is use ajax control toolkit 2.0, 

and now it need to updated to 3.5, but I don't know how to set it up on my project.

In 2.0, I use following setting:

<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="cc1" %>
  ...<cc1:ScriptManager ID="ScriptManager1" runat="server" EnablePartialRendering="true"></cc1:ScriptManager>
,,,

But it not working when reference to 3.5;  How to update, and is there any instruction about that, 

Thanks.