Fixing error

Warning: session_start(): Cannot send session cache limiter - headers
already sent (output started at
/home3/ccm2002/public_html/cmcube/index.php:12) in
/home3/ccm2002/public_html/cmcube/includes/functions.php on line 21

Warning: session_regenerate_id(): Cannot regenerate session id - headers
already sent in /home3/ccm2002/public_html/cmcube/includes/functions.php
on line 22