Running FEniCS tutorial on Ubuntu

I am new to Ubuntu and I've been trying to run the first fenics tutorial, but I keep getting an error that says: No such file or directory.

I downloaded this first program and it is in the downloads folder of my computer, but I can't seem to be able to access it on Ubuntu.

Is there anyway that I could get this file from Ubuntu?

Launch terminal and type commands to add Fenics PPA and install its packages:

sudo add-apt-repository ppa:fenics-packages/fenics
sudo apt-get update
sudo apt-get install fenics
sudo apt-get dist-upgrade

Then test your installation from terminal:

python -c 'import fenics'

Source: https://fenicsproject.org/pub/tutorial/sphinx1/._ftut1002.html