Feed Problem

I have about 2 hours experience with WordPress and RSS now and I am running into a problem that I cant find the fix to anywhere.

My blog is http://www.the-biggest-loser.com/

Now when I click RSS I get a

Warning: Cannot modify header information – headers already sent by (output started at /home/.ergane/bigloser/the-biggest-loser.com/wp-blog-header.php:28) in /home/.ergane/bigloser/the-biggest-loser.com/wp-rss2.php on line 8

From all the fixes it says that I have some whitespace in my files to find em and fix em or replace all the files.

Well I replaced all the files and it still dont work. Though the Comments RSS seems to be working fine.

Does anyone have any suggestions on what to try next?