ok- so I bought 3 reels of blue led lights from Amazon and have no idea how to plug them in. One end of the reel has a plug with a single prong on it and the other end has to wires with no ends on it. I have no idea how to hook it up to a power supply. Did I not order something or am I missing a power supply of some sort or what? The lights are Lighting ever lampux 12 v flexible led strip lights-300 units 3528 leds. help