how to add a classname to javascript and use it in a html table?

[Nazash]

hey guys im trying to use this code:
<script type="text/javascript">
window.onload=function() {
<-------------------->
obj0.onmouseover=function() {
this.style.background='white';
this.style.color='#054c80';
this.style.cursor='pointer';

}

obj0.onmouseout=function() {
this.style.background='#054c80';
this.style.color='#FFFFFF';
}
}
</script>


what im trying to do is plug it in to an html table data<td> ,, i am trying to make a class name in the script.
Does anyone know how you add a class in the script so it will work with my table