Hey, I got 4 of these and am still floundering a little with the SPI.
Do you want to want to connect multiple displays to the Arduino?
If so, you need to wire MOSI and SCLK on all chips together, and wire the SS pin (which Sparkfun calls "CSN") of each display to a different digital output on the Arduino.
Then, instead of using a #define'd constant like "SLAVESELECT" as Busaboi's code does, you'd use a variable, and set it to the digital output pin number for the display you want to update.