I'm a newbia at Unix but I installed for learning the 9.10 32 bits version and intead of the prompt i would like to have a windows interface. I tried to install the xorg program but can't find it. Is there another way?
Ubuntu Server only installs the basic console, but you can add the full X-windows desktop with this command:
sudo aptitude install ubuntu-desktop
That will install the ubuntu-desktop meta package and pull in all required packages.
However, it may be easier for you to download the non-server Ubuntu LiveCD and reinstall from there.