Ubuntu 704 Server - Package management with apt and dpkg

To update the local list of packages, enter in a Terminal:

sudo apt-get update

To install all available updates:

sudo apt-get upgrade

To see if package including the words blah is already installed:

dpkg -l '*blah*'

To install a package:

sudo apt-get install package

To remove a package:

sudo apt-get remove package

To list other apt commands and options:

apt-get help

Also try Aptitude for more interactive package management tool
sudo aptitude