Checking your Ubuntu Version
There are two ways to check which version of Ubuntu you are running. You can either check from within Unity, or put in a short command line in the Terminal.
Unity is the default desktop environment since Ubuntu 11.04 (Natty Narwhal). Please note that this method will only show a partial version number. If you need a full version number like 14.04.1 LTS instead of 14.04 LTS you will need to use the terminal method.
Open System Settings
Click on Details
Your version will be shown under the Ubuntu logo.
In the Terminal
This method will work no matter which version of Ubuntu or desktop environment you are running.
Open the Terminal (keyboard shortcut: Ctrl+Alt+T)
Enter the command lsb_release -a
Your version will be shown on the Description line.