Inner Joint to joint 2 tables in cart

Hi all!

I'm facing a situation that is a little up my knowledge.
I have a cart (see code below) in a ecommerce site that prints the number of itens/REF/Products name/Packing/Unit price/sub_total.
My database is divided in 2 tables (one for the products name and other for the REFs).
I want to ad in the printed results the correspondent description that I have in the table with the REFs.
like this:

number of itens/REF/Products name/PRODUCT DESCRIPTION/Packing/Unit price/sub_total.
I think I must use Inner Joint but don't know much about it!
Any one can help me with this?
Hope that I made my self clear. Thanks in advanced.

António

<?php

while($row = mysql_fetch_array($result))
{
$id=$row['itemId'];
$qtd=$row['qty'];
$preco=$row['euro'];
$preco_desc=$row['preco_desc'];
$cod=$row['codigo'];
$idprd=$row['produto'];
$qry = mysql_query("select * from produto where id = $idprd ");
$campos = mysql_fetch_array($qry);

// Increment the total cost of all items
if ($preco_desc<>"" and $row['promocao']==1){
$preco = str_replace(",",".",$preco_desc);
}
else{
$preco = str_replace(",",".",$preco);
}

$Subtotal=floatval($preco)*$qtd;
$totalCost += floatval($preco)*$qtd;
$Subtotal=str_replace(".",",",$Subtotal);

//@mysql_query("insert into cart (cod) values(sdsdf) where cookieId = '" . GetCartId() . "' and itemId = $id");
@mysql_query("update cart set preco = '$Subtotal' where cookieId = '" . GetCartId() . "' and itemId = $id");

?>
<tr>
<td width="12%" height="25"><div align="left"><font face="verdana" size="1" color="black">
&nbsp;
<?php $id=$row['itemId'];?>
<?php echo $row["qty"]; ?> </font> </div></td>
<td ><div align="left"><font face="verdana" size="1" color="black"> <?php echo $row['codigo']; ?> </font> </div></td>
<td width="33%" height="25"><div align="left"><font face="verdana" size="1" color="black"><?
//print"<a href='detalhe_prod.php?ler=$campos[id]&cod_cat=$campos[id_titulo]'> $campos[produto]</a>"
echo $campos['produto'];
?></font> </div></td>
<td width="14%" height="25"><div align="left"><font face="verdana" size="1" color="black"><?php echo $row['empacotamento']; ?> </font> </div></td>
<td width="14%"><div align="left"><font face="verdana" size="1" color="black"> &euro;<?php if ($row['preco_desc']<>"" and $row['promocao']==1){
echo $row['preco_desc']; }
else{
echo $row['euro'];
}
?>
</font> </div></td>
<td height="25"><div align="left"><font face="verdana" size="1" color="black"> &euro;<?php echo $Subtotal; ?> </font> </div>
<div align="center"><font face="verdana" size="1" color="black"> <a href="cart.php?action=remove_item&amp;id=<?php echo $row['itemId']; ?>"></a> </font> </div></td>
</tr>
<?php
}

// Display the total
?>