Setting up a FTP Server
 

Hey guys im planning to setup our own FTP server using our UBUNTU desktop. Currently our connection given by our ISP is a PPoE which requires a username and a password, but they also gave our routable IP address. How ca n i setup our FTP Server's connection settings with these? this server also acts as our gateway and a proxy server.

None of that information is required to configure FTP. PPPoE authentication would not be handled by the FTP daemon, and the FTP server is going to be largely oblivious to it's external IP (unless you have a specific reason to bond it to that address).

You just need to install/start the FTP server, make sure the ports are open in your firewall, and go. I would suggest looking into some guides about securing FTP servers, though.