So what is the significance of irc in hacking? Well it is place where most of the hackers meet. There will be group discussions on hacking and many other things you need to learn. Just join a group and learn through the group discussions. It also supports file transfers between connected users, using a method called DCC to transfer data. So you can share resources also in irc.
You can do internet relay chatting by downloading an irc client. There are different irc clients for different operation systems. For windows its mirc, ircll for linux, snak for mac etc. Download one of the clients and start chatting with hacker.