Or, you can download either of them at the bottom of the page. Most IRC networks limit it to 9 characters or less. Be warned, other users get upset when a user changes names often. Usernames have little relevance if you are not connectiong from a multiuser system, but one needs to be provided nevertheless. While almost anything will be permissible, eight or less alphabetic characters is preferred.
Channels are chat areas of a particular topic.
You MUST be in a channel to chat with others. Note that not all clients support this command. Leaves a message saying that you are not paying attention. Very useful for when you are away from the keyboard for a short period of time. 6667 Oort does not require a password.