Naturally you mean fluently ,with no pronunciation mistakes and enough expressive as a native ,well that would take long time , and mingling with natives help a lot to pick up the accent , the manner and expressions of the natives ,in what you like to call "natural" . Reading and speaking helps you a lot too ,but it is a matter of time and effort :)

Perhaps the best way to speak naturally is to speak with native english speakers and you'll pick it up....learning a language can be easy but speaking it naturally takes time. You could also read english newspapers or online articles....that might help...