I have been using Mirc for almost a year now, but i havnt used in the last month or so, now i still connect just fine to the server, but when i try to join the channel i always use( karaoke realm) it says » #karaoke-realm Cannot join channel, channel allows registered nicknames only (+R), i have paid for Mirc so it is registered but now i just forget how to register my nick!! Anybodys help would be greatly appreciated!!!! THANKS!!!

mIRC doesn't have anything to do with a IRC Server.
» #karaoke-realm Cannot join channel, channel allows registered nicknames only (+R)

That means you need to register your nick. It depends on what irc server you are using, the way you register your nickname. Most common way is with NickServ, try /msg nickserv help on the IRC Server you connect to.

Also, some networks do not have "NickServ" but rather something similar. For example, Austnet has NickOP and ChatNet has DogTag, and so on. It varies from network to network, but NickServ is more common. Should you connect to a network that may have something similar but you do not know what it is, check with the networks help channels or websites for more.