Outdoor motion sensor lighting

[Navat604 (R.)]

Something like this? Outdoor floodlight motion sensor mod.

Looking for Outdoor Night Motion Sensor and lighting?

I already have flood lights with motion sensors - you have a link on the product page for just adding a relay under these circumstances, but I don’t see instructions for proper setup (the link just takes me to purchase the relay). How do I add the relay? Is it wired behind the flood light? Or is it wired at the switch for the floodlight?