EDIT 3 : It was pointed out by commentors that this is not a true SPI. After looking further, I can see this information, which I missed in original :
The strips basically implement a large shift register, like SPI, but with a small trick to allow use of only 2 signals – data and clock, without a separate reset or latch signal. Each LPD8806 implements six 7 bit PWM controllers, but six daisy chained 8 bit shift registers (effectively a single 48 bit register). With a 1 metre length, and 32 LED/m, that gives a total of 32 * 8 * 3, or a 768 bit shift register.
DELETE THIS : The Digital LED Strip that you are using communicates via Serial Peripheral Interface (SPI)
In your particular device, the data transmission is one way only. Meaning you only send signals and do not receive signals.
Other than the power and ground, your data transmission uses SCLK (clock) and Dout (data you are sending). Dout is often referred to also as MOSI (master out, slave in), where your controller is the master, and the LED is the slave.
CS (chip select) doesn't seem used on your LED string, but is normally used to select a particular slave to talk to.
The frequency of your SCLK will be determined by your controller software.
EDIT 1 : Adafruit says the LED strip uses the LPD8806 controller. Data sheet for LPD8806
EDIT 2 : Further information on data transmission This page here