adding ajaxStart to jquery

adding ajaxStart to jquery

Greetings I've been trying to add ajaxStart function to my code unsuccessfully. This is what I have so far which is working. I just need to add ajaxStart to my existing jquery so that when a user clicks submit and requests a html page you can will see a loading or an animated gif while the user waits for the page to load. I've been looking at the ajaxStart documentation but I still can't get it working. Any suggestions please.