esp8266 starting tips

nodemcu site
My boards respond to being treated as nodemcu types.
Blink works when using their
pinMode(BUILTIN_LED, OUTPUT); // Initialize the BUILTIN_LED pin as an output
.
A further test would be to fade, the brightness of, an LED. This is likely to require an additional LED (, resistor pair) on another pin. The LED used to blink is located near the USB connector.
So I need to find the value of BUILTIN_LED but actually, the resistor + LED pair on PCB is next in importance.
pinouts
schematics
arduino website

useful but not directly relevant to above situation:
serial port on Pi
at command set
current ability
github manual
source for above pages