Can´t login to Admin… please help

Hello…
I’m new to wordpress. I have just finished the installation and i think i did everything right because the default blog ins online:
http://www.asescolhasdesofia.com/escolhaszine
The thing is when i try to access the administration page i put the username and the password that was given to me and… I get a blank page…
What did i do wrong?

Thanks