This is what I use for a starting point when I write an Arduino sketch for my display. It's heavily commented to explain what is going on. I'm sharing this because I wish I'd have seen this somewhere when I got started. Hopefully somebody will get some use of it. And do whatever you want with it.

Code:
//---------------- Picaso librarys ---------------
#include "Picaso_Serial_4DLib.h"                //
#include "Picaso_const4D.h"                     //
//------------------------------------------------

//-------Various Arduino setups-------------------
//#define DisplaySerial Serial                  // Uncomment if using AR shield or Pins 0, 1 and comment out Serial2 line
#define DisplaySerial Serial2                   // Mega 2560 digital pins 16 & 17, no unplugging to upload
// Uncomment the following 2 lines and comment out Serial2 line if using sofware serial and set pins accordingly
//#include <SoftwareSerial.h>                   //
//SoftwareSerial DisplaySerial(2,3) ;           // pin 2 = TX of display, pin3 = RX
Picaso_Serial_4DLib Display(&DisplaySerial);    //
//------------------------------------------------

void setup() 
{
  // ------------ Initialize screen --------------
  //     Call these functions in this order..   //
  //     Do not address the screen before or    //
  //     within this group.                     //
  delay(2000);                                  // wait for screen to power up
  DisplaySerial.begin(255000);                  // set baud to whatever screen is running
  Display.TimeLimit4D = 5000;                   // 5 second timeout on all commands
  Display.gfx_ScreenMode(LANDSCAPE);            // set orientation (PORTRAIT or LANDSCAPE)
  //----------^--- End initialize ---^------------

  //----------- Show Display Model ---------------
  char mdl[20];                                 // these lines are just to show the screen model
  Display.sys_GetModel(mdl);                    //   in the upper left corner of the display and
  Display.gfx_MoveTo(0, 0);                     //   can be commented out
  Display.putstr("Model=");                     //
  Display.putstr(mdl);                          //
  delay(1500);                                  //
  //----------------------------------------------

  //---Mount uSD-Uncomment if using uSD card------
  int mnt;                                      //
  Display.gfx_Cls();                            //
  Display.putstr("Mounting...");                //
  mnt = Display.file_Mount();                   //
  Display.txt_MoveCursor(1, 0);                 //
  if (mnt) Display.putstr("Mounted");           //
  else Display.putstr("Not Mounted");           //
  delay(1500);                                  // optional pause to display mount status, comment out to skip
  //----------------------------------------------

  //--------- Enable touch and touch region-------
  Display.touch_Set(TOUCH_ENABLE);             //
  Display.touch_DetectRegion(0, 0, 399, 239);  // set this to the dimensions and orientation of your screen
  Display.gfx_Cls();                           // clear the screen
  //----------------------------------------------

}

void loop() 
{
  
}