How is night prayer offered?

[The non-obligatory ] night prayer is a voluntary prayer performed after sunset and before dawn. As for tahajjud, it is a voluntary prayer performed at night after waking up voluntarily, and for the sake of God the Almighty Who says: “And pray in the small watches of the morning: (it would be) an additional prayer (or spiritual profit) for thee: soon will thy Lord raise thee to a Station of Praise and Glory!”[17: 79]. Offering tahajjud is better than offering voluntary prayers before going to bed.
And God the Almighty knows best.