How do I make an unanchored door that returns to its original position?

I want to make a train game, but have no knowledge of scripting. I need doors that fade out and in (or just allow the player to run through, just as long as it still is not transparent when the player starts driving around), but I also want them to be able to move with the train. Please help.

For your moving the doors with the train part, put the train doors inside of the actual train so whenever you move the train, the child parts also move in the same direction.

And with your main part, you would have to change Orientation through script, for example :

script.Parent.Touched:connect(function() -- Make sure to put a script inside the door
	script.Parent.Orientation = Vector3.new(orientation number here) -- Changing the Orientation
	wait(3) -- Waiting 3 before next line of code
script.Parent.Orientation = Vector3.new(original orientation number here) -- Resetting the Orientation back to its original value

Hopefully this helped out :D