How to make a proper lightsaber with animation.

I just done shooting a film and I'd like to make it a Starwars look-alike. So I want to know; how do you make a beautiful lightsaber that follows a certain source of movement.

I've tried to use the Neon Rectangle tool and made me a lightsaber, though it wont move at all.

I've tried to move it pr. frame but it just move it in all the frames. I've tried to use the Motion Trail tool but it just wont work proper.

Please help me