1.Create an account here
2. Install World of Warcraft. You can download it (legally) from here: Windows or Mac. Make sure to upgrade to our current supported patch, which is 2.4.3 and 3.3.5 a. Patch mirrors can be found here.
3. After your download is complete, open realmlist.wtf.
4. Erase all text and change it to: set realmlist 127.0.0.1
You may now start playing! If you need any help, do not hesitate to create a support ticket.