Jquery Call asp.net page method.

Question

How can I use a jquery ajax script call my asp.net page method?

ajax script

$.ajax({
                type: "POST",
                url: "./register.aspx/registAccount",
                data: "{loginname:'" + tbUserName + "',realname:'" + RealName + ",password:'" + tbPassword + "'}",
                contentType: "application/json; charset=utf-8",
                dataType: "json",
                success: function (msg) {
                    // Do something interesting here.
                    alert(msg);
                },
                error: function (result) {
                    alert(result.status + " " + result.statusText);  
                }
            });

and I added the http model as

"<httpModules>    

<add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>

    </httpModules>"

But I the script still return a error "500 error"

Your reply is highly appreciated!