the headers already sent error is caused by output on the page between closing php tags "?>" and opening php tags "<?php".
The output can be a blank space, blank line, text or html.
The error is reporting the output around line 9 of the registration page in this section of the message:
output started at /home/beeritu/public_html/registration.php:9
see the following thread for more details on the error and troubleshooting it: