By default, your Arduino IDE will not recognise the D1 mini from the LIGTHBO.LT webshop. But no hurry, it's very easy to fix this ;-)

Prepare your Arduino IDE to recognize a D1 mini board (ESP8266)

Open Arduino IDE and go File > Preferences:

ArduinoIDE-File-Preferences.png

In the Additional Boards Manager URLs, enter the URL http://arduino.esp8266.com/stable/package_esp8266com_index.json:

ArduinoIDE-Preferences-Additional-Boards-Manager-URLs.png

Press OK.

Go now to the Board Manager: Tools > Board > Board Manager. Search in the Board Manager for esp8266 and click on Install:

Specific settings needed in Arduino IDE to be able to use the D1 mini (ESP8266) board

You can now select the right board in Tools > Boards > ESP8266 Boards > LOLIN(Wemos) D1 R2 & mini. 

And additonally, change the Upload Speed (Tools > Upload Speed) to match 115200:

Your Arduino IDE is now ready to push some code!