When I ask you to write a review of a scholarly article there are a number of things you need to do.
-Pick an article. (assuming I have not done it for you) Theoretically you could pick anything. In practice you need to look for something that is enjoyable and that you can review. (Just like a book review) By enjoyable I mean something that you are interested in. There are zillions of articles out there, why waste your time on something you don't want to do? The article also has to be something that you are capable of commenting on. If is is a highly technical discussion of the development of the hermeneutics of hadith under the Abbasids and you have no idea what any of those words mean it is probably not for you. A review-able article is one that you can engage with and say something about. Note that if I have asked you to select an article part of your grade is based on how well you have done at it. If you have picked a rotten article you can't say much about it and thus can't get as good a grade as someone who picked a good article.

-Let me know what the article says. In most cases I will not have read this article, and in a review you should always assume that the reader has not read what you are writing about. People often use reviews to help them decide what to bother reading or even as a substitute for reading. So you need to tell the reader what the basic argument of the article is and how it is developed. 

-An article is supposed to say something and convince you of some point. What was this one trying to do and how well did it do so? The author is not just stringing words together, they are constructing an argument, and you need to explain how they are doing it.

-Evidence is quite important in assessing an article. How is the author proving things? What sort of sources are they using? You need to be critical of what they are doing. This involves a certain amount of arrogance. The author obviously knows a lot more about this topic than you do, but you still need to be able to point out if there are places where the arguement is not as strong as it could be. You also need to be a little modest. If you can't understand what the author is doing be sure that it is their fault rather than yours. You may have to do a bit of research to figure out what the author is saying. If you realize that you are not following the article because it keeps using terms like bakufu or hoplite you might want to look them up. 

-How does this article fit into the wider literature? You will not be able to answer this question as thoroughly as a more experienced historian, but you should be able to do a fairly good job of it. What does this article tell us that is interesting or important, that relates to some question or topic that historians are interested in? To some extent all articles are good, in that they tell you more than you knew before about the specific topic they are dealing with. A really good article sheds light on larger themes, however, and you should explain how it does that. 

-All article reviews should include a full citation. All late assignments will be graded down one mark a day i.e. an A- becomes a B+