If you are using Adept Manager, you can just open Adept, select View/Manage Repositories, then find the line/lines Universe, right click on them and select 'Enable', then click 'Apply' then 'Close' then 'Fetch Updates' Then your good to go, you can do the same for 'universe multiverse' etc if you like.
If you use Synaptic, Settings/Repositories, then tick the box/boxes you want, click 'OK' then reload.
That's the easy GUI way anyways.
To do it the manual CLI way, open a terminal/konsole and type,
sudo kate /etc/apt/sources.list (click enter)
type in your password, find the lines containing the universe repo's and remove the # from in front of them, eg
#deb
http://au.archive.ubuntu.com/ubuntu/ edgy universe
#deb-src
http://au.archive.ubuntu.com/ubuntu/ edgy universe
would become,
deb
http://au.archive.ubuntu.com/ubuntu/ edgy universe
deb-src
http://au.archive.ubuntu.com/ubuntu/ edgy universe
Do that for what ever repo's you want, eg, universe multiverse, save the file and exit. Load up your package manager, Adept or Synaptic, and either "Fetch Updates" or 'Reload' depending on which you use.