The Debian package manager version of WordPress is pretty wonky. If you use it you won't be able to follow any of the installation instructions found here on the Codex.
It's much easier to install WordPress yourself.
First remove the Debian package:
apt-get remove wordpress
apt-get autoremove
apt-get purge
Now install WordPress by downloading and unzipping it to your chosen directory and follow the 5 minute installation directions.