$ sudo apt-get update
# checks to see what updates are needed.
$ sudo apt-get upgrade
# upgrades your software
$ sudo apt-get dist-upgrade
# adds new software as need to upgrade your system ….
Ubuntu developers are always updating and streamlining are operating system so 20 minutes plus isn't bad for your 1st upgrade.
If your looking to install Minecraft on Ubuntu 12.04 many of us are using the how to on this page
To open a terminal press ctrl+alt+t all at the same time. Then cut and paste the following commands into the terminal window one box at a time.