The example is fairly generic so you can adapt it to your specific needs. Because AJAX is so useful, we’ll try out jQuery’s AJAX module.

Do you need to perform an Ajax file upload with pure JavaScript? This example lays out the steps to accomplish an Ajax file upload without the need for a JavaScript library like jQuery or Dojo.

I would say have a good look at some of the JQuery tutorials. There's nothing wrong with doing the JS yourself; JQuery just makes it easier ...