Tried to install Quick Cache - Lots of trouble with my site

[daimion]

I tried to install Quick Cache and it seems to have really messed up my site. When try to log out and check the cache, I get the following message:

//Added by WP-Cache Manager
Warning: Cannot modify header information - headers already sent by (output started at /home/content/30/6063930/html/wp-config.php:2) in /home/content/30/6063930/html/wp-login.php on line 353

It repeats over and over again. I also notice that this appears at the top of all my pages - both the site and the admin panel:

//Added by WP-Cache Manager

How do I get rid of that message, and how do I stop the repeated warning messages?