I would like to make a sensor that detects when my car is clear of a certain point. So, when backing in my car to my garage, I would have a beam and sensor. When the beam is broken, an LED light would turn on and then when the beam gets through, the light turns off and I know that the car will clear the garage door.
I am pretty sure I have to use either an Arduino or Raspberry Pi, but I'm completely new to home automation. There are a few other things I'd like to do but this is a good starter.
I don't know where to start.