Can't Find a Supervisor

[Joseph]

I am trying to install avast from my desktop and this is what I get:

ragweed at ragweed-den:~$ sudo apt-get install avast4workstation_1.0.8-2.deb
E: dpkg was interrupted, you must manually run 'dpkg --configure -a' to 
correct the problem.
ragweed at ragweed-den:~$ dpkg --configure -a
dpkg: requested operation requires superuser privilege
ragweed at ragweed-den:~$

Ok, I thought I was the supervisor for this machine.  How do I run it as 
supervisor?  Why should I have to run it as supervisor?  I've installed 
things before and didn't have to do it as a supervisor.

Any thoughts?

Joseph