Say what? Are you asking how to setup an ftp server on your box? Check out www.proftpd.org
and get/install that server. After, do a search on this site for a few examples of config files, edit yours to your needs and start your server.
Also, head over to www.noip.com
or wherever you want to get your free DNS name from, and sign up; assign your DNS to your IP, and go. If you have a dynamic IP, then you'll want to look at one of the dynamic free DNS providers out there (as shown above in the links provided) and use their update clients to update your ip when it changes.
Then, for someone to access your ftp server, they go to ftp://yourchosenname.no-ip.org
(or whatever you choose to use) and they will be accessing your server.
From there, it's as easy as removing anonymous access, and forcing a user/pass setup.
IF that's not what you meant, post back with some clarification...