the entries are very system-dependent and must therefore be checked again for each Linux-OS. For many Linux-OS based on Ubuntu the procedure is as follows:
if you want to log in automatically, i.e. without entering user and password, so that the graphical desktop starts immediately, you have to add (as root) the following file:
/usr/share/lightdm/lightdm.conf.d/60-lightdm-gtk-greeter.conf.
At the end of this file write with a text editor a new line with the following content:
autologin-user=odroid
(Instead of odroid you take the username you want to log in with)