but that really has nothing to do with ftp
if a user connects to your server with an ftp client, he is connecting to an ftp service on an ftp port - not through http
you can't connect an ftp session from your server to the client, as only a tiny percentage of client machines have an ftp service set up
if a client wants a file off your server, you just put a hyperlink to the file on a web page, they click it, and it downloads over http... nothing at all to do with ftp