How to read values in ASP from jQuery

Question

$(function () {
        $("#button").click(function () {
            alert("You clicked Submit button");
            $.ajax({
                type: "POST",
                url: "Insert.aspx",
                data: "{'StudentId': 'B1111' ,'StudentName': 'Likhit'}"
            });
            $("#studenttable").append("<tr><td>B1111</td><td>Likhit</td></tr>");
        });

Above is my jQuery function. 

sid = Request.QueryString["StudentId"].ToString();

This is how I am trying to retrieve data from function. But it's not working."

An exception of type 'System.NullReferenceException' occurred in App_Web_kqkv5dqo.dll but was not handled in user code

Additional information: Object reference not set to an instance of an object.

" 

 Help me with suggestions.