No problem at all ^^
I'm just saying, avoid inputing commands that you do not understand. The tutorial you're following can be a little tricky, and there's a risk if doing something bad if you miss a step or something.
You probably do not need the nvidia drivers. I used Ubuntu for 2 years without ever needing to install them. However if you insist on doing it, I suggest you:
1- Follow the
official tutorial. The tutorial you showed me seems a bit advanced and is simply looking for the 'latest' drivers. The official one will work as fine.
2- Read a general Linux/Ubuntu tutorial. Do not use something like
sudo without understanding permissions or ownership.
In any case, proceed with caution and if you have any other question, do not hesitate to ask :)