Replacing an "Alphanumeric 16x2 LCD" with a "Smart-GPU color 320x240" display...

What have you tried to make it work? The examples show how to write text on the display, so you should at least be able to have a go at converting this bit:

      lcd.setCursor(0, 0);//where to start cursor
      lcd.print("PINA SYSYTEMS       ");//print message
      lcd.print("SOFTWARE VERSION 1.0");//print message
      delay(2000);
      lcd.clear();  
      
      lcd.setCursor(0, 0); // set the cursor to column 0, line 0
      lcd.print("PP1");  // Print a message to the LCD.
  
      lcd.setCursor(6, 0); // set the cursor to column 6, line 0
      lcd.print("PP2"); // Print a message to the LCD
  
      lcd.setCursor(12, 0); // set the cursor to column 12, line 0
      lcd.print("PP3");  // Print a message to the LCD.