1. install desktop environment: `sudo apt-get install task-xfce-desktop`
2. Log-out and then before you log back in, select "Xfce" from the "session" menu.
If that didn't work, you **might possibly** need to reset your login manager to the default settings, by running (for example) `sudo dpkg-reconfigure gnome-session`, or whichever session manager you are currently using.
