IRC is a chat-protocol that's established itself over many years. It's the basis for several IM clients, though most people who use them would never guess, since basic IRC is fairly 'techy' to get into.
Or, at least, that used to be true.
mibbit is a website that allows anyone to join any IRC 'channel' (this is the IRC lingo for 'chatroom') with minimal knowledge of how IRC works. If you're just looking for a way to connect to where we hang out, head over to that page and use the mibbit login there.
If you'd like a short introduction into the most common IRC commands, though, read on.
There are a couple of terms fairly unique to IRC, but they basically mean the same things you're used to from other areas. The trick is simply knowing what the matching term is.
Channel, as already alluded to, is a simple IRC-moniker for 'chatroom'.
Op is short for channel operator, which is synonymous with moderators elsewhere.
Voice is a little tricky to explain. Channel ops have the ability to put a channel on express moderation, which removes the right of anyone without a voice (or an op) to speak. If a channel is not on express moderation, though, a voice has no effect and no meaning, though in the Wildcard-related OOC channels you'll find it is used to denote roleplayers.
/mode +m - this is the express moderation channel mode mentioned above.
/mode +c - some IRC clients allow users to use colour. Our channels prohibit this with the +c mode. Don't worry, though, that doesn't mean messages with colour get lost - the colour is just stripped from them.
Normal chat is not prefixed with anything. Just type away! Hello! will show up as <pinkgothic> Hello! if your current name is 'pinkgothic'. Note that your message may not begin with a / (slash), since that denotes commands in IRC.
Commands? Well, a simple example would be actions:
/me prefixes an action. If you want to tell the channel that you just laughed, you could do so by typing /me laughs. This will show up as * pinkgothic laughs. if your nickname is 'pinkgothic' at the time.
/nick newnick changes your name. Yes, changing your display name is that easy in IRC - no one really owns nicknames, unless they registered them, so you're free to change your display name to whatever you like, whenever you like it. Moderators can identify you regardless of your current name, so don't worry about this being a security hole.
/join #channel joins a channel called '#channel'. For example, you might want to type /join #dataclaw to join #dataclaw.
/server irc.serv.er tries to connect to an IRC network 'irc.serv.er'. To connect to Darkmyst, you would type /server irc.darkmyst.org.
There are plenty more commands, but most of them aren't relevant from the get-go. Many IRC clients make your life easier by giving you a user-interface in which you don't have to type all IRC commands by hand.
These days, IRC should never be intimidating. If, though, you find yourself at a loss, Darkmyst has extensive help pages, or you can ask anyone in #dataclaw for help.