lightdm autologin
in order to automatically login a user on a xubuntu or any other linux that runs lightdm you can simply add the user to your lightdm.conf file
edit the file in /etc/lightdm/lightdm.conf and add these two lines to the SeatDefaults block:
autologin-user=myUsername autologin-user-timeout=0
of course you need to replace myUsername with your actual username.
keep in mind that once you have this option set encrypting your home directory is probably very pointless… so if you want your user data protected don't use autologin!