How to perform search using AJAX?

Hi,

I have following HTML code:

<table style="border: 1px solid #9f9f9f; float:right;">
<tr>
<td><label for="status">Search Status</td>
<td><input type="text" id="status" name="status" dojoType="dijit.form.TextBox" size="40" value="Please enter search criteria"/></td>
</tr>
<tr>
<td><label for="push">Push to start</td>
<td><button dojoType="dijit.form.Button"  style="width: 4em" type="button" name="submitButton" value="Submit" onclick="loadDoc()"></button></td>
</tr></table>

I want that when a user enter some keyword in the textbox and hit button, there is a Ajax call to retrieve search results from a simple txt file kept on my local. Please guide how do I achieve this? I have written loadDOC method which simply retrieves the txt file contents but I want it search based