The style you mention in the paper is not something I am familiar with. Although I said I'd answer no questions about the paper, this one seems to be about your particular ability to do what is asked. Thus, I will answer it. It is the style of every case you read in the class. A judge makes a decision according to the law and writes an opinion explaining it.
Judges try to base their decisions on existing law, applying the facts of the particular case to it.
NOTE that you must address each issue raised. You have to decide if, given the facts, the plaintiff can prove his case. If they do establish the case, then if the defendant's defenses all fail, the plaintiff wins. If, on the other hand, the facts establish the plaintiff's prima facie case, but the defendant has a valid defense, then the defendant wins. That's it in a nutshell.