I found this site, Serna On Ubuntu, today when I was searching for information on codecs. It is a couple of years old but there are notes to help you where that might be an issue.
It has a great article on Using the Command Line If you’re new to Linux I think this is a must read! It’s also worth following the links in the article and reading each of these pages too – Entering Commands, Using The Terminal, Navigating Directories, Files and Directories, Working With Text Files, Piping And Direct Output and Background Tasks.
It’s been brilliant for me to read too as there are many gaps in my Linux knowledge and things I’ve forgotten as I’m no longer maintaining systems or a network.