How to connect LED driver to arduino
Connect up to SCK, MOSI, and a pin for Latch. I wouldn't use SS in this case due to the load/ pin wanting to be low most of the time.
To send in data:

SPI.transfer(byte1);
SPI.transfer(byte2);
digitalWrite (load, HIGH); // latches the data
digitalWrite (load, LOW); // updates the output register


OE/ connects to Gnd unless, or a PWM pin for brightness control.

analogWrite (PWMpin, 10);  // lower for brighter, higher for dimmer