php - Submit button returns to index page instead of sending data -

here link website - http://zigzagadvertising.com.ph/aleemguiapal/page/2/

i have problem regarding forms in wordpress. whenever click on submit button returns index page instead of sending data email address

this php code placed on top of header.php. code placed before tag

<?php  $error=false; $sent=false; if(isset($_post['submit'])) { if(empty($_post['firstname']) || empty($_post['email']) || empty($_post['message'])) { $error = true; } else {   $to = "clestcruz@gmail.com";   $name = trim($_post['firstname']);  $email = trim($_post['email']);  $comments = trim($_post['message']);   $subject = "contact form";   $messages = "name: $firstname \r\n email: $email \r\n comments: $message";  $headers = "from:" . $name;  $mailsent = mail($to, $subject, $messages, $headers);   if($mailsent){      $sent= true; } } } ?> 

and custom page(contact page)

<!--contact--> <div  class="container"> <div  class="eleven columns contact">      <div id="contact-container" class="eleven columns alpha omega contact">          <h2>contact us</h2>          <p>lorem ipsum dolor sit amet, consectetur adipiscing elit. cras non lacus vel nulla molestie cursus quis urna. donec sodales venenatis consequat. sed tristique elit nec diam rhoncus adipiscing</p>      </div>       <div id="note-container" class="eleven columns alpha omega note">          <p>all fields marked asterisk(<span class="asterisk">*</span>) required</p>      </div>       <div class="contactform">      <form id="register-form" action="<?php echo $_server['php_self']; ?>" method="post">        <?php if($error == true) { ?>      <p class="error"> there misisng fields.</p>      <?php } if($sent == true) { ?>      <p class="sent">thank sending message</p><?php } ?>            <div class="four columns alpha contact-form">           <label>prefix</label>          <input type="text"  />          <label><span class="asterisk">*</span>first name</label>          <input type="text" name="firstname"/>          <label><span class="asterisk"></span>middle name</label>          <input type="text" name="middlename"/>          <label><span class="asterisk"></span>last name</label>          <input type="text" name="lastname"/>          <label><span class="asterisk">*</span>email address</label>          <input type="text" name="email"/>          </div>          <div class="four columns contact-form">           <label>phone</label>          <input type="text" />          <label>street</label>          <input type="text" />          <label><span class="asterisk"></span>zip</label>          <input type="text" name="zip" />          <label><span class="asterisk"></span>city</label>          <input type="text" name="city" />           </div>          <div class="clearfix"></div>          <div class="eleven columns contact-form alpha omega">          <label><span class="asterisk"></span>subject</label>         <input type="text" name="subject"/>         <label><span class="asterisk">*</span>message</label>         <textarea name="message"></textarea>           <input class="contact-button" type="submit" name="submit" value="submit" />         <input class="contact-button" type="reset" value="reset" />          </div>       </form>      </div>  <div class="four columns"> </div>  </div>     <?php get_sidebar(); ?> </div>      <?php get_footer(); ?>    </body> </html> 

i tried making contact page , uploaded free hosting site , seem working properly. got data or values in forms. not sure if reason why forms not working because of wordpress itself.

if want have form submit current page set method empty string:

<form action="" method="post"> 

personally, i'd separate out logic form header.php separate file cleaner code organization. in separate file use

header('location: http://whatever.com/contact'); 

to redirect after you're done processing form data.