Finding Multimedia Software
Finding additional software for Ubuntu Studio can be done in numerous ways and from various sources.
Finding Software From the Ubuntu Repository
Using Software Center
The Software Center is the default Ubuntu software manager, and is the easiest way for new users to browse and look for new software. All the software listed there is available to you through the common Ubuntu Repository where all the official Ubuntu packages lives, including all the Ubuntu Studio related packages.
While you will find that you can find mostly everything you need using Software Center, not everything in the Ubuntu repository is installable from there. In those cases, you will need to use either Synaptic or Apt at the command line.
Synaptic Package Manager
Synaptic is no longer installed by default on Ubuntu, so you will need to first install it to make use of it. It is a bit more technical, but once you get the hang of it, you might prefer it to the Software Center.
Apt is a great command line tool for searching for packages. Open a terminal and type: apt-cache search ubuntustudio, and you will get results of all the packages installable that relate specifically to Ubuntu Studio. (see FAQ about using the terminal)
Once you find a package you like, install it with: sudo apt-get install <mypackage>
Sometimes you will find that an application does not exist in the Ubuntu repository, or that you would like to install a custom version of that application. Often you will find such applications on separate PPA's (personal package archives), which are available at Launchpad.
If you have found a PPA repository that you would like to use, you will find the instructions for adding the repo to your system and making those packages installable on the same page. Generally, it is something like sudo add-apt-repository <some-ppa-repo>
Separate Ubuntu Packages
Sometimes applications will only be found on their specific websites. The easiest way to install an application manually is to find a Ubuntu .deb package for it, download it, and double-click to start the installation.