Registration site is broken – Help?

Hello guys!

I tried to edit the URL, on my registration site, but right now, the registration site seems broken.

I get this message when i’m trying to connect to the page:

Warning: Cannot modify header information – headers already sent by (output started at /var/www/mindcology.dk/public_html/wp-config.php:90) in /var/www/mindcology.dk/public_html/wp-includes/pluggable.php on line 875

Thanks!