How to echo multiple rows with data based on checkbox input?

How to echo multiple rows with data based on checkbox input?

Got stuck trying to echo out multiple rows with data based on checkbox
input. As of current code it processes data from only one checkbox, no
matter how many checkboxes are ticked. Please help!
while($row = mysql_fetch_assoc($r))
{
$pals .= '<input type="checkbox" name="pal_num[]"
value="'.$row['pal_num'].'">'.$row['pal_num'].'<br>';
}
if($pal == '') {
echo '';
} else {
echo '<form name="get_pal" action="post2.php" method="POST">';
echo $pals;
echo '<input type="submit" name="post" value="Go!">';
echo '</form>';
}
post2.php:
$w = $_POST['pal_num'];
$rrr = mysql_query("SELECT * FROM pl_tab WHERE pal_num".$w[0]);
while($row = mysql_fetch_array($rrr))
{
echo '<tr><td>'.'&nbsp'.'</td>';
echo '<td rowspan="5">'.$row['descr'].'</td>';
echo '<td><b>'.'Total weight'.'<b></td>';
echo '<td>'.'&nbsp'.'</td><td>'.'&nbsp'.'</td></tr>';
echo '<td>'.'&nbsp'.'</td>';
echo '<td colspan="3">'.'&nbsp'.'</td>';
//this part should multiple based on how many checkboxes are ticked.
echo '<tr><td>'.$row['l_num'].'</td>';
echo '<td>'.$row['pal_num'].'</td>';
echo '<td>'.$row['weight 1'].'</td><td>'.$row['weight 2'].'</td></tr>';
}
echo "</table>";}