The first time you run your IRC client program you have to fill in some information about yourself, such as, your Internet address and the IRC server with which you want to connect. It's usually best to try and connect to a geographically close server, even though that may not always be the best. In general, the port number to use is 6667. A port number should be seen as an entrance to a server. Normally you do not need a password to use an IRC server.
Most servers allow anonymous access.
If you do not have a password for an IRC server then leave the password entry field blank. If you are prompted for a login or password and you dont know what to type, try to connect to another server. However, simply filling in nonsense will not make you anonymous. IRC is not inteded to keep you hidden from your friends or enemies. Keep this in mind if you are tempted to behave maliciously.