#include 
LiquidCrystal lcd(2,3,4,5,6,7);
void setup()
{
  lcd.begin(16,2);
}
void loop()
{ 
  lcd.setCursor(0,0);
  lcd.print("Hello World !"); 
}

Explain :
Step 1: First we add library of lcd display screen.
Step 2: LCD pin (2,3,4,5,6,7)
Pins connections:-  LED- connected to ground having resistor 1kilo ohm.
					LED- connnected to ground.
					DB7- to Digital pin 7
					DB6- to pin no. 6
					DB5- to pin no. 5
					DB4- to pin no. 4
					E(Enable)- to pin no. 3
					R/W (read/write)- ground connection
					RS - pin no. 2
					V0 - ground with resistor 330 ohm
					VCC- power 5v
					Gnd- ground.
Step 3: void setup() initialize lcd(16,2)
Step 4: set the loop. setCursor(0,0)- means first (columns, row).

OUTPUT: