You have to have a brain made of carbon deposits to not be able to figure out how to use this.
Slip it on the exposed cable, slide down to the housing, tighten and then connect your can with attachment on the nozzle to the little opening on the side.
Geeze, walk in to any bike shop and ask... or ask your neighbour's 7-year old. They'll figure it out easy enough.
I recommend the luber with the two screws but this one works fine enough.