How install Xorg and a windows manager on Ubuntu server?

[alelinuxbsd]

Today i installed Ubuntu server 12.04 (64 bit edition) and i want install Xorg and a windows manager as icewm but when i make:
apt-cache search Xorg
apt-cache search icewm
i don't find anything.
Where i'm wrong?

As you can see there isn't anything wrong:

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://it.archive.ubuntu.com/ubuntu/ precise main restricted
deb-src http://it.archive.ubuntu.com/ubuntu/ precise main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://it.archive.ubuntu.com/ubuntu/ precise-updates main restricted
deb-src http://it.archive.ubuntu.com/ubuntu/ precise-updates main restricted
...

but don't work.

[HermanAB]

Install LXDE.

[alelinuxbsd]

Was sufficient update the packages.
sudo apt-get update
sudo apt-get upgrade
After that i installed:
sudo apt-get install xserver-xorg-core icewm xfe firefox xinit

With vi i add on .xinitrc
exec icewm-session