[IRCHelp](http://www.irchelp.org/irchelp/new2irc.html) is a good resource. For clients, the [webchat](webchat.freenode.net) is easiest, because you don't need to install anything and it's cross-platform. [ChatZilla](http://chatzilla.hacksrus.com/) is almost as easy -- it's a Firefox extension, and works anywhere Firefox does. For a dedicated IRC application, [Pidgin](http://pidgin.im) works decently (or [Adium](https://adium.im) on Mac), and has a familiar instant-messenger-style interface. For something truly dedicated to IRC, there's [mIRC](http://www.mirc.com) for Windows (free), [LimeChat](http://limechat.net/mac/) for Mac (free), or [Textual](http://www.codeux.com/textual/) for Mac (paid). There are also many other clients out there, but those are some good recommendations for people relatively new to IRC.