Apart from power and ground (and power to the LED backlight if there is one) There are four basic signal lines to an SPI device. They are;

MOSI or Master Out Slave In which is also known as SIMO and SDI; DI, DIN, SI: because it is Serial Data In. It lets the master send data to slave.

MISO which is Master In Slave Out aka SDO; DO, DOUT, SO which allows the slave to send data to the master. It isn't always there.

SS which is Slave Select and is also known as SCE, nCS, CS, CSB, CSN, nSS, STE which switches sending between master and slave.

SCLK which is the clock pulse. It's attached to an oscillator of regular frequency.

In a nutshell it works like this: you set the slave to receive. You send a bit of data every time the clock pulses. When you've sent all the data, you set the slave to transmit. It then knows it's got to process something and does it. It sounds hard but it isn't- it's exactly what we do with shift registers.
If you look at the pin out above of the LCD module, you'll see three of the four- there's no MISO because it does not need it. There are other pins that are used for controlling the PCD8544 and they are:

D/C which selects between data and commands being sent.
RST which is a reset
GND which is the negative terminal
VCC which is the positive and needs 3.3V

Right up at the top is LED which is where you attach 3.3V and not 5V or you'll blow it up. It powers the backlight. Here is a wiring diagram from Sparkfun that shows you how to attach it to an Arduino Uno:


This shows the screen on a breadboard. If you want to use it on a breadboard, then you'll need to solder in some headers as the module comes unpopulated. Alternatively you could solder on some jumper wires and stick them straight to the Arduino. Despite what the drawing says don't provide 5V- it will not end well.

Now we need some code to drive the Arduino. Over the page is a monster which provides a demo of some of the things the module can do.
Copy and paste it to your Arduino IDE by highlighting the top section, scrolling down the page to the bottom shift & left click to highlight all, then CTRL C to copy and CTRL V to paste.
Pay attention to the pinout and all pins except the power supplies and GND (3.3V for backlight and board supply) need to go to to the Arduino board via a 10k resistor, except SCE which uses 1k.