<form action="" method="post" class="ajax_form af_example form-horizontal">
  <div class="control-group">
    <label class="control-label" for="af_name">Имя*</label>
    <div class="controls">
      <input type="text" id="af_name" name="name" value="" placeholder="Введите имя">
      <span class="error_name"></span>
    </div>
  </div>
  <div class="control-group">
    <label class="control-label" for="af_email">E-mail*</label>
    <div class="controls">
      <input type="email" id="af_email" name="email" value="" placeholder="Введите email">
      <span class="error_email"></span>
    </div>
  </div>
  <div class="control-group">
    <label class="control-label" for="af_phone">Телефон</label>
    <div class="controls">
        <input type="text" id="af_phone" name="phone" value="" placeholder="Введите номер телефона">
      <span class="error_phone"></span>
    </div>
  </div>
  <div class="control-group">
    <label class="control-label" for="af_message">Сообщение*</label>
    <div class="controls">
      <textarea id="af_message" name="message" rows="5"></textarea>
      <span class="error_message"></span>
    </div>
  </div>
  <div class="control-group">
    <div class="controls">
      <button type="reset" class="btn btn-default">Очистить</button>
      <button type="submit" class="btn btn-primary">Отправить</button>
    </div>
  </div>
</form>