<form action="/get.php" method="get">
<select name="sehir">
<option>Ankara</option>
<option>İstanbul</option>
</select>
<select name="renk">
<option>Mavi</option>
<option>Kırmızı</option>
</select>
<input type="submit" name="Ara">
</form>

<?php
$_sehir=$_GET['sehir'];
$_renk=$_GET['renk'];
?>