Nurpawiki can be installed in various ways. By far the simplest method is to use the Nurpawiki Debian package.
Debian installation: installing Nurpawiki on Debian.
If you successfully installed using the above link, you can stop reading now.
See Debian DB instructions for instructions on installing using Debian's packages. This should work for both Debian and Ubuntu. The instructions should be easily adaptable for other distributions.
See DB from source for installing everything from source (not recommended).
See here for more configuration options.
Point your browser to http://localhost:8080/view?p=WikiStart and login as "admin" (leave the password field empty).