I have a wotlk client already can I use that and if I can what is the realm info

[sunnypally]

I just don't know

[skullatbash]

yes, you should able to use your client. follow this guide to change realmlist: http://forum.warmane.com/showthread.php?t=290754
If it does not work then download the client from here and you willbe fine: https://www.warmane.com/download