Documents which required before installing of NodeMcu Dev board
https://www.silabs.com/products/mcu/Pages/USBtoUARTBridgeVCPDrivers.aspx
##Arduino Board manager :
Copy and past to additional boards manager URL in preferences
http://arduino.esp8266.com/stable/package_esp8266com_index.json
##Arduino Tool :
open Board and select boards manager
then TYPE " NodeMcu" and Install ESP8266 core for Arduino IDE . :
then follow the examples