ok now i know what you mean. i was in the wrong directory. i don´t have access to my "logs" directory. how can i change the .htaccess file without have access to this?
Either connect to your 1&1 account by FTP or SSH, go into your Joomla folder. Inside that folder you will find a htaccess.txt file. It is That file you will need to rename to .htaccess (period in front important) and then edit that file and add the php line to the very bottom of that file on its own line.