Ubuntu is a Debian base Linux distribution with backing from Mark Shuttleworth via Canonical Ltd.
Upgrade to the last version:
sudo apt-get install update-manager-core sudo do-release-upgrade
General system updates are handled with:
sudo apt-get update sudo apt-get upgrade
But if when doing the updates you ever received a message stating "The following packages have been kept back" you'll need to issue the following (thanks to http://www.debian-administration.org/articles/69):
sudo apt-get dist-upgrade
If you're on Telstra then edit /etc/apt/sources.list with http://mirror.aarnet.edu.au/ubuntu/dists/ with the result that anything from there won't count against your cap.