A long press on the power button image will make a URL request to ESP8266 with the variable and value you set in the options.
For which the ESP8266 must manage this request having an HTTP server, if you want the program to change the red button on the green, you must return somewhere in the web code (hidden or visible) the STATUSIS=HIGH character chain.
Enter the IP ESP8266 manually or let the program seeks it.
You can download a sample of working code with the program at:
<a href="https://www.google.com/url?q=https://www.google.com/url?q%3Dhttp://37.187.4.185/server_toggle.lua%26sa%3DD%26usg%3DAFQjCNHVNXh3_hin5EnEnsE9PTM1mUYnHQ&sa=D&usg=AFQjCNHUx-nhm6sTkYmIEsgxDXnO9DmgJw" target="_blank">http://37.187.4.185/server_toggle.lua</a>