<script language="JavaScript">
function test(t) {
    for (var i=0; i<t.rows.length; i++)
    for (var j=0; j<t.rows[i].cells.length; j++)
    t.rows[i].cells[j].bgColor = t.rows[i].cells[j] == event.srcElement ? 'red' : '';
}
</script>
<table width="300" cellspacing="1" bgcolor="black" onClick="test(this)">
<tr bgcolor="white" height="20"><td> </td><td> </td><td> </td></tr>
<tr bgcolor="white" height="20"><td> </td><td> </td><td> </td></tr>
<tr bgcolor="white" height="20"><td> </td><td> </td><td> </td></tr>
</table>