Step 6: Program Board/Write PHP
first open the PHP file and make the following changes:
set $path to the location of Sender.exe
set $port to the COM port the arduino is using
save the PHP file to the htdocs folder in your XAMPP directory as index.php
load the Arduino IDE and open the Arduino file. Press the reset button on the Arduino. Then, quickly press the transfer button in the IDE. Once the file has transferred, you're done.