My site www.1800designershades.com gets these errors on the top

Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at /home/oneeihb3/public_html/index.php:18) in /home/oneeihb3/public_html/includes/functions/sessions.php on line 108

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/oneeihb3/public_html/index.php:18) in /home/oneeihb3/public_html/includes/functions/sessions.php on line 108

Warning: Cannot modify header information - headers already sent by (output started at /home/oneeihb3/public_html/index.php:18) in /home/oneeihb3/public_html/includes/init_includes/init_templates.php on line 78

Anyone have a solution please?