Having problems with 3.3.5a install on MAC.

Heya

Trying to install it, I tried to follow the steps on a guide from this forum, but I don´t understand it really well. I downloaded what seems to be the installer, but I can´t open it, says error or something like that. So if someone explain me how to download and install it (in easy steps, please) or give me any direct download link, I would appreciate it so much!

Thanks.

Ps: I don´t really mind which language it is, I understand english and spanish.

And how did I install your client on mac? I downloaded from main site and copy launcher and wow.app to applications. Nothing happened when I opened game.