maybe it would be better to make that still-image line in photoshop (because of the infinite creative posibilities in that software) and then import it to AE and “draw on” it.
In tutorials section you should find a very very good tutorial called something like “making ornamentals”, that would be a good help.
By the way, is your light spot an animated point with vectors? or is it a movie imported to the proyect?
see you