How do i move a sprite across the stage using the arrow keys on my keyboard?

Question

I'm a high school student and i love director. I recently have become interested in game development, and i am completely lost in how to move a sprite across the stage. I have tried toying around and google hasn't been very helpful. An example of something i found is
on keyUp
  if (_key.keyCode = 124) then sprite(4).locH = sprite(2).locH -25
  if (_key.keyCode = 123) then sprite(4).locH = sprite(2).locH -25
end keyUp
I don't understand why this wont work.
HELP

Answer 1

This code moves sprite 2 to a position relative to sprite 4. If sprite 4 is not moving, then sprite 2 will always move to the same position, so it will not appear to move at all.
Perhaps this code makes more sense:
on keyUp
  if (_key.keyCode = 124) then sprite(2).locH = sprite(2).locH +25
  if (_key.keyCode = 123) then sprite(2).locH = sprite(2).locH -25
end keyUp