Ngspice on ubuntu

I am installing ngspice on my ubuntu and using ubuntu for the first time so I am not exactly familiar with the commands.
I found the instructions on this link
sudo apt-get install build-essential linux-headers-uname -r
When I entered the above command as it is, it said ‘unable to locate package’

Also I downloaded the ngspice as mentioned but couldn’t tar and gunzip the files. Please help