Exemple of code to end-node

Hi, I´m trying to connect my device from Heltec LoRa WiFi BLE 32 v2 with the same code that I used with TTN. I need help with an example of code to make sure that I´m doing the right way.

On the Chirpstack plattaform I got the Dev EUI and the App Key. The App EUI is equal to 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00.

Thanks for the help!