How to upgrade Ubuntu 14.04 LTS to 16.04 LTS Desktop

a)
$ sudo apt-get update

b)
Upgrade all installed packages to new version
$ sudo apt-get upgrade

c)
Upgrade to latest version of distribution
$ sudo apt-get dist-upgrade

d)
Check version
$ lsb_release -a

e)
Upgrade to latest release
$ sudo update-manager -d

f)
Check version
$ lsb_release -a

OR

a)
Open "Software Updater" and upgrade all packages to new version

b)
Upgrade to latest release
$ sudo update-manager -d