I have a www-data that was automatically set up when I installed Apache. I have a ftpuser that I configured myself to use with ProFTPd. I use a MySQL database with users that use this user to log on.

The problem is that Apache with PHP is working as it should, but I cannot add files with FTP. I tried to do chmod 777 mysite.com, and it worked, but now Apache gave me a 500 internal error. I suppose chmod isn't the correct way to go. I deleted my folder and made a new one.

How can I give ftpuser permissions to read and write, while www-data should not loose its permissions. I don't have much experience with Linux command line.

Thanks!