Correct Pins for Nodemcu 8266
The v0.9 and v1.0 NodeMCU boards have 2 LEDs: One on the AIthinker module, and one on the actual NodeMCU board.

The AIthinker module's LED is connected between Vcc (3.3V) and GPIO2 (labeled D4 on nodeMCU). It turns ON when D4 is set LOW.

The NodeMCU LED is connected between Vcc (3.3V) and GPIO16 (labeled D0 on nodeMCU).  It turns ON when D0 is set LOW.

The pin labeled RST is the Reset signal from the AIthinker module, and is active-high, meaning you connect RST to GND to put the device in a reset state.

The pushutton labeled FLASH is connected between GND and GPIO0 (labeled D3 on nodeMCU). When the this pin is LOW when the ESP8266 comes out of a reset state, the chip is in flash-bootloader mode, meaning it is ready to receive a new sketch. On a NodeMCU, however, the ESP8266 chip is placed in flash mode by the USB chip and the flashing software, so there is not a need to manually press this button.