I was speaking recently to one of my students. I asked him how we was getting on with the report that he had to write for me. He said, "It's going well. I've done it! I just need to translate it into English!"
I was lost for words! (It's a nice phrase to describe those times when you just can't think of anything to say, isn't it?) The more I think about it, the more lost for words I am! When I think about what makes a good academic piece of work at a British university, all sorts of things come to mind (if you want to review my article on the features of academic English now would be a good time and you can find it here) but I doubt that many of those things would be present in a piece of work translated from another language.
Writing in your first language means thinking in your first language. It means that you will use features of your language and your culture. You cannot write an introduction in your first language and then just translate it to English; an introduction to a report or essay in English will have different features to a report in a different language - especially if your language and culture is very different to English. My student needs to firstly plan his piece of work (in English!) in order to get a good idea of the structure, and write it in English.
I talked to the student and asked him how he had planned his report, and he admitted that he hadn't planned it before writing it.
You wouldn't build a house without a plan would you? You wouldn't drive around a new country without a map would you? I suggested my student read this article about the importance of planning your work here.