Question about anonymous ftp

I have some files on my site which can be downloaded by users by http. The files are in a subdirectory of "public_html", say "public_html/files" .
How can I give acces to users for these files by anonymous ftp? I made a symbolic link in the directory "public_ftp", but when I connect with anonymous ftp account , i can't see the link.
I used the commands "cd ~/public_ftp" and "ln -s ~/public_html/files" . The symbolic link files can't be viewd by anonymous ftp. To duplicate the files is not a good solution because I add or update them sometimes and I would be forced to duplicate them each time I add or update a file .
Could you please tell me how resolve this problem ?

Thank you