Publishing your feed means putting a copy of your feed on a webserver so it is available for others to access, subscribe, download, etc.
If you webserver is on your local network, then it might be as easy as saving your feed file to the proper shared folder. However, for most people publishing will mean uploading your feed file to a webserver using FTP (file transfer protocol).
In order to upload you feed to your webserver you will need a few pieces of information to start with:
1. The web address of the FTP server (many times the same address as your webserver)
2. The username needed to log into the FTP server
3. The password needed to log into the FTP server
4. The location on the server where the RSS feed file should go.