I'm not sure the button is something you would do with FTP. That's something you simply connect to using an ftp client.
For what you are talking about (downloading from a button on a web-page) you'd usually use a script. I've written my own scripts to handle that sort of thing here.
Even so, I thought we had included anonymous ftp in your account when we set it up.
[PS EDIT] I think you just need to put files you want to share via anonymous ftp in your anon_ftp directory. Though as mentioned, this isn't what you want to do here.
The easiest way: If you just want people to access your software directly from a web-page link, you can just put it in a web directory and give them a link to it. Make sure you upload it BINARY.