如何在警报中显示AJAX响应消息？

I am sending username and password as request parameter to the server in AJAX and trying to show the response message. But not able to showing the response message.In fiddler it is showing the response message. But while on the browser screen it is not showing.PLEASE somebody help me out where i am wrong or need to change anything.. I have written like this-I am sending username and password as request p