Warning: Cannot modify header information

Hello,
I have an issue with the WordPress site I am using.
Whenever I try to go to the wp-admin page, or post anything I am getting an error message saying:

Warning: Cannot modify header information - headers already sent by (output started at /home2/fcoacoma/public_html/wp-content/themes/freelance/functions.php:9) in /home2/fcoacoma/public_html/wp-admin/post.php on line 222

Warning: Cannot modify header information - headers already sent by (output started at /home2/fcoacoma/public_html/wp-content/themes/freelance/functions.php:9) in /home2/fcoacoma/public_html/wp-includes/pluggable.php on line 875

Other forums have said that this can be caused by white spaces in the wp-admin.php file.
Either way I have tried to get rid of all white spaces in all main php files and the rest I just replaced with original untouched WordPress files.

One other thing I noticed is that it is only a particular theme that is giving me the error. So I would say that the problem would have to be inside the theme itself. However my knowledge of code is amateur at best so any help would be greatly appreciated

The website is at http://www.fcoa.com.au

Cheers,
Will.