form.html
<form action="display.php" method="POST">
<select name="month">
<option value="January">January</option>
<option value="February">February</option>
</select>
<input type="submit" value="send it">
</form>
display.php
if(!isset($_POST['month']))
echo "You must select a month!";
else
{
echo "You have selected $_POST['month']";
}