1. Turn on ESP8266 and to connect to its open WiFi network from a personal computer, a smartphone or a tablet.
2. Launch a web browser and to visit http://192.168.4.1/
3. From the HTML5 web page select WiFi network, type password (if applicable) and click Connect.
These features are provided by the open source project ESP8266-jadja https://github.com/leon-anavi/esp8266-jadja
For more information please have a look at: https://www.anavi.org/article/184/