I know how to do this with classic asp.
How do I do it with ASP.net?
Can I just make a code page like verifyLogin.cs
And call that page from Jquery?
Or would I have to make a page like verifyLogin.aspx with a code behind page?
There are lots of different ways to do it, depending on your requirements. Here's a very simple way to start though. Create a page called "AjaxData.aspx" with no code-behind:
<%@ Page Language="C#" %>
<%
Response.ContentType = "text/plain";
string data = "some data";
Response.Write(data);
%>
Then use your AJAX call as normal:
$.get("AjaxData.aspx", function(data) {
alert(data);
});