I. You download one of the clients :
1.RedCabal client
2.Cabal EU
3.Cabal US
and so on ....
II. You download the patch of the server you want to play . You can find all servers here :
1. You extract all files in your game client directory and replace them
2. Register for the server you want to play
3. Log in and play
III. (Optional) For chinesse private servers you download the english patch . You can find it at the end of the link I gave above
Note : You should better install East Asian language pack if you choose to use RedCabal client .
Have fun