Once you’ve added the BLYNK_TEMPLATE_ID and BLYNK_DEVICE_NAME to your sketch, configured the correct board type, and uploaded the sketch to your board you are ready to do the provisioning.
It’s always a good idea to have the board connected to your computer and the serial monitor open so that you can see the debug information that’s being provided in the serial output.
The LED on the board should be flashing quickly.
Open the app and tap the three horizontal bars in the top right-hand corner then tap “+ Add new device”. Choose “Connect to WiFi” and confirm that the device is ready to be provisioned (LED blinking) by tapping “Ready” in the app.
The app will then scan for devices waiting to be provisioned, show you the device details and ask for permission to join the network (select Join), then ask you to select the SSID and enter the WiFi password.
Once you’ve done this the data is sent to the device and stored in its EEPROM, and you can exit the “Add device" when asked (Apply, Done, Exit to App).
The device will then appear on the initial screen of the app, ready to have widgets added to its mobile dashboard.