I recently got a new user account for Ubuntu 12.04 on Linux after becoming unable to log in to one of my earlier accounts. I can log in to this account easily enough, but when I try to use the password to install software through the Ubuntu Software Center, it reads:
Your authentication attempt was unsuccessful. Please try again.
I tried installing the software through the terminal with this:
sudo apt-get install
But when I entered my password, I got this message:
[username] is not in the sudoers file. This incident will be reported.
I searched the forums for a solution, and I found this thread, which told me to open a root terminal. I don't know how to do this, but I found out I could get a root terminal by entering this in a normal terminal:
Upon doing this, I was asked to enter my sudo password, and I got the same message as before. What am I missing or doing wrong?