It may look simple on paper, but this will be a very challenging project for a beginner. However, such a system is certainly possible and you can find a number of useful examples on the web.
Start with Arduino by spending some time with the example projects, learning to blink an LED, etc. then move on to something more challenging, like connecting to the internet (you will need an ethernet, wifi or other Arduino compatible interface).
Then figure out how to use the internet to connect to the Arduino and command it to blink an LED.
When you get that far, you are ready to think about more serious challenges.