Can't start the game after download..

Help please!

After donwloading wow (mist of pandaria for windows) at warmane for almost an entrie day i finally wanted to play, but it does not open!!!!
About a minute after clicking on the wow.exe there opens a message saying: "Data/enGB/wow-update-enGB-18273.MPQ: World of Warcraft can’t make a required change to an archive file. Be sure you have write permission for the World of Warcraft folder or try running the game in administrator mode. For more information, see: https://battle.net/support/article/6910

I have already tried to open the game as an admin and without fierewall but it doesn't help.

Now my head hurts and im very disappointed!
Sorry if i have overseen any topic that explains my problem but im not able to search now because my head just hurts bad!
fufufufufu

http://i.imgur.com/5wWKUL6.gif