AVG antivirus install in Kubuntu

[WJ Seidl]

Could someone please help a (real) Linux newbie with an install of the 
free version of AVG anti-virus?
I'm on a newly built P4/Celeron 3.56Gig with a gig of RAM running Feisty 
(7.04)
I've only been exposed to Linux for three days now since the install, 
(after 12 years on MS Windows) so my knowledge is limited.
(Thank god for Adept, or I wouldn't have a clue.  I have a book or two 
on order, but they haven't arrived yet.)

Long story short, I downloaded and installed the program (the 7.5.45.deb 
version, not the rpm version)
and it seems to work, but will not update.  When I click (in the GUI) on 
the update button,
  the return is "Update process failed. Reason: Sorry, you do not have 
permission to execute avgupdate."

Someone "suggested" that I need to add root to the group. Ok, fine. 
Um...could someone please explain how?
Many TIA,
WJS