apt-get install PACKAGE_NAME
Is the command used to install any package you know the name for, like
sudo is used to earn root access and be able to install and remove software.
sudo is always required if you do system wide changes like installing, removing, updating and upgrading packages.
Is the command used to manage any software and software sources. install is an extra command that tells the computer that you want to install software with the package name as follows. It will then check the software sources for a download link with the same name and then download and install the latest version (or specified version).
will update the sofware sources with new versions of the software listed (not installing anything)
upgrades the software if new versions are available in the software sources.
removes the package name specified after (like install).
there are more useful commands, but these are necessary for getting started with managing software from the terminal.
After more research on aptitude i found out that it's already installed. So installing aptitude wouldn't resolve in anything besides errors in the conosle. Start aptitude by:
aptitude package is a GUI version of the
apt-get command, it hasn't got the full set of features as apt-get but you have the basics like,
install, etc. More information about
aptitude and it features can be found here.
Also search in the software center if you want o use a GUI to find and install/uninstall applications.