My wordpress blog got hacked

Sorry for posting twice in two different forums but I really need help with this.

I set up a new WordPress 2.1 installation on my blog. 2 days later, here’s what my webpage looks like:

Casus Team Was Here For TurkeY
Fatal error: Call to undefined function: wp() in /home/meteor00/public_html/wp-blog-header.php on line 16

For some reason, they got past WWW-Authentication and got into my files and deleted the database, leaving graffiti. What happened? I’m not good at WordPress and I’m new.

To add insult to injury, this was posted on a website:

http://www.zone-h.org/index2.php?option=com_mirrorwrp&Itemid=43&id=5621644