You say the installation was successful. Do you mean you chose the option "Desktop Environment" during the stage called "software select and install" or something similar? If you're only logging in command line, then you'll have to install the GUI--GNOME or KDE environment--from the CLI.
I believe this will install everything that GNOME should have.
If you want KDE, then IMP
: For the apt-get to work, you must have root privilege--