First, give a brief (one paragraph) summary of the article. What were the main points? If there were studies described, what was the basic method of the studies? What conclusions did the author(s) draw?
Next, discuss in a paragraph how the paper is related to what you already know. This could be a relation to other aspects of psychology (perhaps things you learned in other classes). It could also be a relation to other areas of knowledge. You might relate the article to something from another discipline. You might also relate it to something from your every day life. Any of those is fine.
Finally, give a reaction to the paper. Do not react to the writing style. Chances are, you will find papers from the research literature frustrating to read at first. This frustration reflects that you are just learning how to read these kinds of papers. Instead, try to react to the ideas. Do you think the authors point of view is reasonable? Would you approach the same problem in a different way? Are there aspects of the paper that you think are very likely to be right or wrong?
The whole reaction paper should be about a page. Beware, it takes some work to write only a page. In order to fit all three aspects of the reaction into a page, you need to think a bit about exactly what you want to say.
Remember that the reaction papers are due in class on the day that the article is listed on the syllabus.
Good luck.