I can't log in

Hi Guys,
I've downloaded the two versions os MoP on site. But i can't log in...
Do you have a tutorial explaining how to get started?

Thanks.

"but I can't log in"... what does it mean? Can you give us more info? what error message do you get?

Be sure your password has less than 16 characters

if it's the same eroor as I'm getting it's about updating to a blizzard server, or blizzard server version or something. I also play on MoP