Basic apt tutorial.
Apt looks at your sources.list file to find the download servers for all software to install. Package managers such as synaptic also look at your sources.list file. This file is located at /etc/apt/sources.list. Apt is a very useful and powerful tool that is very easy to use. Synaptic is a GUI interface available in the gnome desktop environment to control apt. Adversely Kpackage does the same thing in the KDE desktop environment.
If you want to search for a package you can use apt-cache
apt-cache search <package name>
To install a package use apt-get install
apt-get install <package name>
To Remove a package use apt-get remove
apt-get remove <package name>
When removing software in some files such as configurations are not always removed. To completely remove a package use the purge switch
apt-get remove --purge <package name>
To fix broken packages use the force option with install
*** Note there was not a package name specified here. This is intentional.
To perform a system update use apt-get upgrade
To perform a distribution upgrade use apt-get dist-upgrade
To re-load your sources.list file use apt-get update
using the above information you should be able to do almost anything related to package management on your system.