How is light used in television?
Like how do we see it?
And what is torque?

Well, that completely depends on the type of television.

Have a read of cathode ray tube, LCD, Plasma display, LED, and Video projector.

I'm not sure what you mean by how do we see it... you might want to read up on the eye.

Torque is the angular parallel of force. Read torque.

Hope those links help.