<form class="form-horizontal modal-trial-form" method="post" action="sendmail.php">
<fieldset>
<div class="form-group">
<input id="ad" name="ad" type="text" placeholder="Ad Soyad" class="form-control" required>
</div>
<div class="form-group">
<input id="telefon" name="telefon" type="text" placeholder="Telefon" class="form-control" required>
</div>
<div class="form-group">
<input id="mail" name="mail" type="text" placeholder="E-Mail" class="form-control" required>
</div>
<div class="form-group">
<select required id="otopark" name="otopark" type="text" placeholder="Otopark" class="form-control">
<option disabled selected value>Otopark Seçiniz</option>
<option value="Şişhane">Şişhane</option>
<option value="Büyükçekmece">Büyükçekmece</option>
<option value="Zeytinburnu">Zeytinburnu</option>
<option value="Kadıköy">Kadıköy</option>
<option value="Bayatpazarı">Bayatpazarı</option>
<option value="Kemalpaşa">Kemalpaşa</option>
<option value="Vardar">Vardar</option>
<option value="Aydın">Aydın</option>
</select>
</div>
<div class="form-group">
<div class="col-md-12 text-center">
<button class="btn btn-fill btn-lg btn-block btn-submit submit-form-trial" style="color:#fff;" type="submit">Gönder</button>                                             </div>
</div>
</fieldset>
</form>

<?php
include 'class.phpmailer.php';
$mail = new PHPMailer();
$mail->IsSMTP();
$mail->SMTPAuth = true;
$mail->Host = 'mail.parkturk.com.tr';
$mail->Port = 587;
$mail->Username = 'benim@adresim.com';
$mail->Password = 'çokgizlişifre';
$mail->SetFrom($mail->Username, 'Benim Adım');
$mail->AddAddress('alici@adresi.com', 'Alıcının Adı');
$mail->CharSet = 'UTF-8';
$mail->Subject = 'Mail Başlığı';
$mail->MsgHTML('Mailin içeriği!');
if($mail->Send()) {
    echo 'Mail gönderildi!';
} else {
    echo 'Mail gönderilirken bir hata oluştu: ' . $mail->ErrorInfo;
}
?>