Show LED on Blynk

With a micro-controller I want to be able to read the state of my computer (so on or off) with Blynk. I think I can connect the power LED wires from my motherboard to my controller and then program it so that I can see it in the Blynk app. But I don't know how to. Can you help me? Or have you found someone that has already done something like this and explains it somewhere? Any help is appreciated!

Board is WeMos® D1 R2 WiFi ESP8266. (D1 r2 wifi esp8266 development board compatible uno program by ide Sale - Banggood.com)