jQuery - addClass or removeClass - Is there an append class?

Question

I have css hover over images for my tabs and I'm trying to get the class to change from .how to .how_on when I click on the image HOW.

My tabs are

HOW | WHAT | WHEN | WHO | WHY

I have classes for each (.how, .how_on), (.what, .what_on), etc...

Can I make jQuery add _on to the original class name using click(function(){}); ?

HTML:

<div id="tab_container">
     <ul class="tabs">
        <li><a class="how_on" href="#how">How</a></li>
        <li><a class="why" href="#why">Why</a></li>
        <li><a class="what" href="#what">What</a></li>
        <li><a class="who" href="#who">Who</a></li>
        <li><a class="when" href="#when">When</a></li>
    </ul>
    <p><img src="images/tab_top.jpg" width="864px" height="6px" alt="" border="0" /></p>
</div>
<div class="tab_body">
    <!-- HOW -->
        <div id="how" class="tab">
            <strong>HOW IT WORKS:</strong>
        </div>

JQUERY:

<script type="text/javascript">
jQuery(document).ready(function(){
 //if this is not the first tab, hide it
 jQuery(".tab:not(:first)").hide();
 //to fix u know who
 jQuery(".tab:first").show();
 //when we click one of the tabs
 jQuery(".tabs a").click(function(){
 //get the ID of the element we need to show
 stringref = jQuery(this).attr("href").split('#')[1];




 // adjust css on tabs to show active tab





 //hide the tabs that doesn't match the ID
 jQuery('.tab:not(#'+stringref+')').hide();
 //fix
 if (jQuery.browser.msie && jQuery.browser.version.substr(0,3) == "6.0") {
 jQuery('.tab#' + stringref).show();
 }
 else
 //display our tab fading it in
 jQuery('.tab#' + stringref).fadeIn();
 //stay with me
 return false;
 });

});
</script>

CSS:

.tabs
{
    width: 683px;
    height: 29px;
    padding: 0;
    margin: 0;
    display: inline;
    float: left;
    overflow: hidden;
    list-style-type: none;
}

.tabs li
{
    margin: 0;
    padding: 0;
    display: inline;
    float: left;
}

.tabs  a {  background-position: 0 -58px;}
.tabs .on a {   background-position: 0 -29px;}

.how,
a.how:link,
a.how:visited
{
  float: left;
  display: inline;
  width: 135px;
  height: 29px;
  margin: 0;
  text-decoration: none;
  text-indent: -99999px;
  overflow: hidden;  
  background-image: url("../images/how_tab.jpg");
}

Answer 1

When you use addClass, it adds/appends a class unless you remove some first using removeClass, so you do like this:

$('.how_on').mouseover(function(){
    $(this).removeClass('class_name').addClass('class_name');
});

$('.why').mouseover(function(){
    $(this).removeClass('class_name').addClass('class_name');
});

// and so on.........