Things you need:
1. Windows computer
2. Launcher: Client
Follow the steps:
1. Unrar the files in a new folder. (It doesn't matter where you place the folder)
2. Open Wow.exe wich you just extracted from the RAR file.
3. A pop-up window will open, in the left upper corner. (Let it load!)
4. When the pop-up disappears wait a couple minutes and the game starts.
5. Now close WoW en go to your World of Warcraft folder, open Data folder, then open realmlist.wtf
6. Change the realmlist to what ever server you play and save it.
7. Now open Wow.exe again and you can play on the server you want!
Always open World of Warcraft with the Wow.exe not with the Launcher.exe, that's only the Blizzard client!
Have fun playing World of Warcraft.