Call non-static method in server-side from client-side using JavsScript

How do I call a non-static method in server side(aspx.cs) from client side using javascript (aspx)....?

As far as I know I can call static method in server side from client side...

server side:

 [WebMethod]
 public static void method1()
 {
 }

client side:

 <script language="JavaScript">
     function keyUP() 
     {
         PageMethods.method1();
     }
 </script>
 <asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="true">
 </asp:ScriptManager>

It works. Now how do I call non-static method from client side?