<form action="thanks.php" method="post">
<input type="text" name="name" placeholder="Имя" required="">
<select name="menu" size="1">
<option value="first">Первая позиция</option>
<option selected="selected" value="second">Вторая позиция</option>
</select>
<input type="submit" value="ОТПРАВИТЬ">
</form>