How can I become a professional speaker and writer in foreign language?

Watch movies without subtitles, listen to the news, write what you are listening to,know more vocabulary, and at first forget about grammatical mistakes ..

I believe that the principle for learning how things are done is the same throughout the world; if you want to know how to ride a bicycle or drive a car or speak or write etc., all you have to do is do that very action until you come out better. Of course often times there rules and guidelines to follow yet all are directed towards helping us get in a position where we can do what seemed impossible before we gave it a try. Do you want speak and write a foreign language? All you have to do is speak and write, speak and write that language and let the first speakers of the language help to correct your grammar and tenses. Also listen to native speakers as they speak and as well, take time studying various works literature in that language  

You can speakers of that language correct you some of the linguistics technicalities like grammar and tenses, word order and agreement patterns.

Learn the foreign Language in its native country. Visit the local schools, deliver small introductive speeches about your own country and culture, visit the local churches and see how they talk, understand the charm they have and then try again and again.

...  You are  so  kind Thank you Sir Ahmed Ragab