You can find a far more comprehensive tutorial at Power Management & Scheduling via Command Line, but if you want to change just the basic options, a command like this should do it:
sudo pmset repeat shutdown MTWRFSU 22:00:00 wakeorpoweron MTWRFSU 6:00:00
That's the equivalent of going to System Preferences
> Energy Saver
and setting the computer to shut down every day (Monday, Tuesday, Wednesday, thuRsday, Friday, Saturday, sUnday) at 10:00pm (22:00 is military time), and then to power back on all those same days at 6:00am.
You can adjust the options as suits your needs. More details (and more options) in the link above.