Basic installation

I just purchased a Ubuntu computer from Micro center to run gnu radio.
I have never used Linux and I am having a heck of a time installing the
software. The installation guide on gnu radio says to use the command :

apt-get install gnuradio

I am not able to get to the point where I can do this. I have a
terminal program open, I have downloaded gnu radio 3.7.5 and extracted
it into a folder on my lap top. I have navigated to the folder through
the terminal command but when I type the command above I get a message
“Unable to lock administration directory”

I am stuck. Can anyone please help? thanks

Brent

I got my son to come over and help me. The installation page says to
run a single command. Deeper in the gnu radio website there are more
instructions. My son followed them and got it running. I do not know
why the installation page would not point to the other instructions
because it was certainly much harder than typing a single command (as
the installation page indicates) haha