[php] HTML - Change\Update page contents without refreshing\reloading the page

I get the data from DB and display it in a div... what I want to do is when I click a link it should change the content of the div

one option is to pass parameter through URL to itself and reload the page...

I need to do it without reloading\refreshing...

<?php   
    $id   = '1';

    function recp( $rId ) {
        $id   = $rId;
    }
?>

<a href="#" onClick="<?php recp('1') ?>" > One   </a>
<a href="#" onClick="<?php recp('2') ?>" > Two   </a>
<a href="#" onClick="<?php recp('3') ?>" > Three </a>

<div id='myStyle'>
<?php
    require ('myConnect.php');     
    $results = mysql_query("SELECT para FROM content WHERE  para_ID='$id'");

    if( mysql_num_rows($results) > 0 ) {
        $row = mysql_fetch_array( $results );
        echo $row['para'];
    }
?>
</div>

The goal is when I click any of the links the contents of the div and php variable\s gets updated without refreshing.... so that user could see new data and after that if some query is performed it is on new variable\s

p.s I know it is gonna require some AJAX but I don't know AJAX.. so please reply with something by which I can learn... my knowledge is limited to HTML, PHP, some JavaScript & some jQuery

jQuery will do the job. You can use either jQuery.ajax function, which is general one for performing ajax calls, or its wrappers: jQuery.get, jQuery.post for getting/posting data. Its very easy to use, for example, check out this tutorial, which shows how to use jQuery with PHP.