You are using the EPIC irc client. Assuming you have the correct help files for your client, you are using version 4 of EPIC. EPIC is a variant of the ircII client that contains countless enhancements, while retaining near full backward compatibility with ircII version 2.8.2.
EPIC offers a staggering number of features, far too many to describe here. Instead, this document will show you the basics you'll need to get started with irc and with EPIC.
All commands in EPIC are prefixed with a '/'. This is called the command character, and is used to distinguish typed commands from messages intended for a channel. Here are some basic commands that you should become familiar with. In these examples, do not actually include the <> characters when you enter the command.
/help <n> <topic> This is the single most important command available in this client. If you don't know what a command does, chances are it is documented in the online help. When all else fails, look here. The 'n' is a section number, and 'topic' is the command to get help on. If you use /help by itself, a list of sections is given.
/join <channel> This makes you join the specified channel. For all intents and purposes, channels always start with a '#' character.
/part <channel> This makes you leave the specified channel.
/nick <new nick> This lets you choose a new nickname. You may use any nickname you like, as long as someone else isn't currently using it.
/msg <someone> This lets you send a private message to the specified nickname.
/server <server> This lets you switch to a new irc server.
/whois <someone> This will give you some information about the given nickname, such as the person's Internet address, the channels and server s/he is on, etc.
/names <channel> This shows you a list of everyone on the specified channel. You will automatically see a listing for any channel you join.
/list This lets you list all the channels on your irc network. This may not be a good idea, because some networks have several thousand channels.
These commands should be sufficient to get you started. If you want to learn more about EPIC, reading the online help is a good way to start. If you have questions about irc in general, join one of the irc help channels and ask someone. On EFnet, the channel is #irchelp, on Undernet it's #wasteland, and on DALnet it's #dalnethelp.