We have a library with example code ready to go for use with these TFTs. The library is not incredibly fast and optimized but its a good start and can easily be ported to other micrcontrollers. However, we'll assume you're using an Arduino.

Two libraries need to be downloaded and installed: the TFTLCD library and the GFX library. You can install these libraries through the Arduino library manager.

Open up the Arduino library manager:

Search for the Adafruit GFX library and install it:

If using an older Arduino IDE (pre-1.8.10), do the same for Adafruit_BusIO (newer versions do this one automatically).

Then search for the Adafruit TFTLCD library and install it:

We also have a great tutorial on Arduino library installation at:
http://learn.adafruit.com/adafruit-all-about-arduino-libraries-install-use

//comment or uncomment the next line for special pinout! 
#define USE_ADAFRUIT_SHIELD_PINOUT

//comment or uncomment the next line for special pinout! 
#define USE_ADAFRUIT_SHIELD_PINOUT

Restart the Arduino software. You should see a new example folder called TFTLCD and inside, an example called graphicstest. Upload that sketch to your Arduino. You should see a collection of graphical tests draw out on the TFT.