You're going to have to wire in a switch box with a wire coming from the light ceiling light to the switch and then connect the wires as follows; white wire going down to switch connects with black hots and caps off. The white at switch just connect to switch and install switch, The black from switch wire connects to light black and light white connects to ceiling box whites and caps off and then install light and you should be good to go. Attach ground wire , if any, from light to mounting screw
