In Linux, specifically Ubuntu, there are so-called repositories, which are a place where you can find all versions of packages and applications so that the users can later install easily by adding a link of a repository to their system and use apt-get to install software they want, creating a repository is not for new users it is an advanced stage, now you will learn a few basic commands for apt-get.
To install the package :
sudo apt-get install package
Do not forget to replace package to the name of package you want to install.
To remove a package :
sudo apt-get remove package
To remove the pack and all the settings :
sudo apt-get purge package
To check for updates :
sudo apt-get update
To upgrade a specific package :
sudo apt-get upgrade pacakge
To upgrade all packages :
sudo apt-get upgrade
To search for the package :
sudo apt-cache search package
To add a repository from Launchpad :
sudo add-apt-repository ppa: something/someone
Do not forget to replace the text in red colour to the repository, which you find in Launchpad.
To remove the repository from Launchpad :
sudo add-apt-repository - remove ppa: something / someone
To clean up the packages from /var/cache/apt/archives/ :
sudo apt-get clean
To remove the non-required packages :
sudo apt-get autoremove
You can explore more options for apt-get commands in some online guides.