you have a hook end to the spring and that is fed down into the gearbox hole and hooks around the case where it sharpens to a wedge of aluminium.
the other end has an obvious hole in the kickstart mechanism-out it in there. the keyhole shaped ratcheting piece of metal needs to be swung clockwise over the stopping plate until it is at the left end of the said plate.
now press it all down and let go. the keyhole piece will whip anti-clockwise and stop against the right-hand end of the plate which you'll note is raised slightly.
regards
Taffy