MCUFRIEND_kbv v2.9

i am just wondering is there any tutorial or guide for the library MCUFRIEND_kbv v2.9 ?
it is used for control a tft screen. i want to build a osciliscope based on the tft touch shield screen and arduino mega 2560 under this library, but i am no clue where to start

To actually draw on the screen, look at the adafruit library docs.