const char *ssid = "your wifi name";
const char *password = "your wifi password";
const char *serverHostname = "mqtt host name or use broker.hivemq.com for development";
const char *topic = "mqtt topic name";
Compile the code to the board with VSCode PlatformIO or Arduino IDE, Publish a message like on to the MQTT broker you'll see the board built-in LED turns on and send off for turning off built-in LED