Morena or Marron?
Rosetta Stone taught me that "Ella es Marron" means "she has brown hair" while my lesson here said to use "morena"...why?
I think you should use the following phrases: "Ella tiene el pelo castaño\marrón", "Ella es morena".
i learn that to use "morena" always when referring to hair color or skin color of a girl and not to use "marron". This could be more for objects not humans. I also agree with the above posts that if your referring to hair you can just say "pelo castaño" or "castaño oscuro" if the hair is dark brown.
I have always used morano, but I think there are variations based on the type of spanish you are using.
Definitely say "Ella tiene el pelo castaño" because "Ella es marrón" means she is brown. Also, I have been taught to say "Ella es morena" by these lessons and others, but my friends tell me that it really means "She is dark-skinned." It's better to use a term to reference the hair directly and avoid confusion.