Getting input from PC

Hello everyone, I'm pretty new to arduino programming and it would be nice to have some help.

I'm planning an LED board project as a gift so I built a website where the user can select the color of each led in the board.
I need a way to submit the selection of LEDs to the arduino controller without using the IDE. The website is programmed in javascript and the code behind is c#. I can generate a text file with all the properties of each led, but how do I get the arduino to read each of the LEDs properties?

Thanks in advance!!

Serial input basics.

Normally the way something like this would be done is by running a webserver on the Arduino board itself. You would use an Arduino with network connectivity. If you want to connect to the network via WiFi, you could use an Arduino Nano 33 IoT, MKR WiFi 1010, ESP8266, or ESP32. If you want to connect via via Ethernet you would use an Ethernet shield or module connected to an Arduino board.

You can find webserver example sketches in the examples provided with the network library for your board/shield/module.