First off, its THROW, as in to heave in a certain direction.
THROUGH meabs something entirely different.
To answer your question, swithc your secondary fire via the white button, the little icon should change from force push to saber throw. Then simply depress the right trigger to throw your lightsaber. In addition, press x first to target an enemy to throw it at, or you might just waste energy.
For further stupid questions, consult the CONTROLS section of your game manual, or use common sense