How do I join a private server?

I know this sounds really noobish and stuff but how do I join a private server? I need like all the steps..

 

Not too noobish, you should've looked around a little bit, but a anyways;

Once you have world of warcraft installed (and updated to match a private servers current patch) direct yourself to:
.../World of Warcraft/Data/enUS/realmlist.wtf (enUS may differ depending on your language). Open the file (will be prompted with 'open this program with'..choose notepad). And put in set realmlist IP. Ip is listed on the private servers main page/registration page. Just remember to register an account and your set!

 

If you want to play retail as well as servers, you need to make a copy of your WoW folder in another location on your computer.