how to hookup a sainsmart 12 v relay to arduino uno

i bought a sainsmart 12 16 channel relay, but it came with nothing. no specs or diagram for wiring it. i dont want to burn anything out. has anyone used one of these before and know how to wire it to control my leds? i can believe it didnt come with any instructions. i just need to know where to plug the digital output from the arduino uno to it and then where to plug in the leds. i think i found the power input i wired vin from arduino to it and ground off of the arduino

Provide 12V 1A to the relay power inputs.

Connect the Arduino 5V pin to the pins 1 and/or 2 of JP2. Connect the Arduino GND to pins 19 and/or 20 of JP2.

Connect Arduino output pins to pins 3 through 19 of JP2 (relays 1 through 16) and set the pin LOW to turn the relay on.