Do you have a question about the Joy-it RB-TFT1.8 and is the answer not in the manual?
Connect the display to the Arduino pins as shown in the figure and table.
Add the TFT library via Sketch -> Include library -> Manage libraries.
Copy provided code to your Arduino to display text on the TFT.
Connect the display to the Raspberry Pi pins as shown in the figure and table.
Install Raspbian Image using Win32 Disk Imager.
Modify configuration files (config.txt, cmdline.txt, fbtft.conf) to enable SPI.
Install an image viewer, download an image, and display it using the command.
Install fbcp, download a video, and play it using omxplayer.