Adding Users to Existing Groups in Ubuntu (Oneiric Ocelot)

Hi have been working in Virtual Box, this days and need to add my user to the vboxusers group. I was going to do it graphically, and suddenly I notice that the application I use for doing this job it disappear. :(
So I have to use the CLI

If you know the group just do this
Steps

• sudo usermod -a -G GROUP USER
  where -a means append. Add the user to the supplementary group(s). Use only with the -G option. If you want to read more about the usermod do
• man usermod
  

If you don't know the group
Steps

• groupmode 2 TIMES
• sudo usermod -a -G GROUP USER
  If you see the only difference is that you type groupmode and press tab 2 times and all the groups will be display.
  

HOPE it works