Uhm, I don't think this is was bof asked for.
If I understand you correctly you ask how to install DokuWiki on Ubuntu? It could be possible that there exists a DokuWiki package for Ubuntu which is installable through apt-get or it's graphical equivalent (synaptics?). For installing it manually (probably better if you like a current release) just install the apache or apache2 package and the php4 or php5 package. Then follow the description
http://wiki.splitbrain.org/wiki:install.
If you need help setting up Apache and PHP I'd recommend asking in the Ubuntu forums, but do a search before, this is probably described somewhere at their sites already.
If this is not what you asked for you should clarify.