Getting a select option instead of different buttons php class - php

Question

Im trying to get a select between the different sizes of the product. I made a script which echos a button for every size but how can i do this with a select form?
In the DB the product has a master and every size is an option.
To get the product im using ($_GET['add']) to get the product on the cart page.
At the last past im giving the wagen.html?add='.$s['id'] so i can use that id in the cart.
class ProductDisplay {
public function display($content){
global $db, $properties, $cms, $adb;
$content = unserialize($content);
$itm = $adb->queryrow("SELECT * FROM products WHERE id=? LIMIT 1", array(intval($content['wlpid'])));
$vat = $adb->querykeyvalues("SELECT id, multiplier FROM tax");
$prijs = (($itm['price']*($vat[$itm['tax']]/100))/100);
$subs = $adb->queryarray("SELECT *, (SELECT value FROM propertyvarchar WHERE lang=1 AND propid=1 AND product=p.id lIMIT 1) as name, (SELECT value FROM propertyvarchar WHERE lang=1 AND propid=5 AND product=p.id lIMIT 1) as opt FROM products p WHERE master=?", array($itm['id']));
echo '
<div id="the_product_container" class="para_container"></div>
<div id="anchor_1_product"></div>
<div id="anchor_2_product"></div>
<div id="anchor_3_product"></div>
<div id="page_product" class="anchor_pos"></div>
<div id="page_product_check" class="anchor_check"></div>
<div class="bonds">
<div class="scaleme">
<img alt="shirt" class="content" src="/uploaded/overige/'.$content['main'].'">';
$ar = array(
1=>"point_one",
2=>"point_two",
3=>"point_tree",
4=>"point_four",
5=>"point_five",
);
for($i=1; $i<=3; $i++)
{
if(!empty($content['info'.$i]))
echo '<img alt="Product point" id="'.$ar[$i].'" class="'.$ar[$i].'" src="/uploaded/overige/'.$content['info'.$i].'">';
}
echo '</div>
</div>
<div class="mobiel_text_con">';
for($i=1; $i<=3; $i++)
{
if(!empty($content['info'.$i]))
echo '<div class="text_block">
<h3>'.$content['info'.$i.'h'].'</h3>
<hr />
<p>
'.$content['info'.$i.'t'].'
</p>
</div>';
}
echo '</div>';
if(empty($subs))
{
echo '<div class="pricetag">
<p>'.number_format($prijs,2,',','.').' €</p>
</div>
<div class="button_holder_ordernow">
<a title="Order Now" href="/winkelwagen.html?add='.$itm['id'].'" class="sumbit_button">order now</a>
</div>
<div class="photo_overlay_filter2"></div>';
}
else
{
echo '<div style="display:inline-block; text-align:center; width:100%;">
<div class="pricetag">
<p>'.$itm['name'].' ('.$itm['opt'].') '.number_format($prijs,2,',','.').' €</p>
</div>
<div style="display:inline-block;">
<div class="button_holder_ordernow" style=" padding-bottom:20px;">
<a title="Order Now" href="/winkelwagen.html?add='.$itm['id'].'" class="sumbit_button">order now</a>
</div>
</div>
</div>
<div class="photo_overlay_filter2"></div>';
foreach($subs as $s)
{
$prijs = (($s['fromprice']*($vat[$s['tax']]/100))/100);
echo '<div style="display:inline-block; text-align:center; width:100%;">
<div class="pricetag">
<p>'.$itm['name'].' ('.$s['opt'].') '.number_format($prijs,2,',','.').' €</p>
</div>
<div style="display:inline-block;">
<div class="button_holder_ordernow" style=" padding-bottom:20px;">
<a title="Order Now" href="/winkelwagen.html?add='.$s['id'].'" class="sumbit_button">order now</a>
</div>
</div>
</div>
<div class="photo_overlay_filter2"></div>';
}
echo '<br /><br /><br /><br />';
}
}
}
?>