The word "critical" has positive as well as negative meanings. You can write a critical essay that agrees entirely with the reading. The word "critical" describes your attitude when you read the article. This attitude is best described as "detached evaluation," meaning that you weigh the coherence of the reading, the completeness of its data, and so on, before you accept or reject it.
Ask yourself, "Are there other possible positions on this matter?" If so, briefly outline them. Decide on your own position (it may agree with one of the competing arguments) and state explicitly the reason(s) why you hold that position by outlining the consistent facts and showing the relative insignificance of contrary facts. Coherently state your position by integrating your evaluations of the works you read. This becomes your conclusions section.