Problem control a network of Arduinos

Hello! I have an Arduino UNO, I am a bit lost in my project and I'm starting with Arduino stuff now .
My goal is to connect a couple of arduinos to the same network and then be able to send a command to each one of them. Something like: arduino 1 turn on the led, arduino 2 turn off, etc.

But I am not really sure of how to do it, I started with the web client example, connecting all the arduinos to my router, but I do not know how to send a command for each of them.

Any help appreciated. Thanks

I am not sure what approach you are trying and know nothing about web client eg. Have you tried MQTT client running in Arduino?

Without MQTT, you can call each Arduino by the IP, assuming an endpoint listening in each Arduino.

If you are talking about a web network then you need to consider how it works. A server cannot send messages to a client (thankfully). If each of your several Arduinos is programmed as a client they can each make periodic calls to the server to collect whatever new data is waiting for them.