How do I implement personal opinions into an essay?

Uh, guys, I'm not ignoring anyone here. All of your advice had been helpful to me.
At least it helped me into reconsidering what flaws there might have been in my paper and to try and find a way to bypass the problem without trashing the argument altogether.
I always tend to start with the wrongest set of mind which is, kinda: "Everything I do is perfect, it's not my fault, there were no flaws in my writing!" and so on. I'm a bit of a childish writer at that.
But this discussion helped me to cool down and consider the first draft with a different perspective. It's probably true I went too personal on some aspects there, and, when I re-read it, it almost sounded if I was writing, like, a grade schooler paper on my favorite sticker album or something, even to me.
It's also true I wrote on the spur of the moment, only with little knowledge I had of the book since I had just finished reading it, without researching the book's critique first.
My teacher probably noticed it and told me to reformulate it but she didn't want to give me too much advice since it was part of the exam coming up with the argument and writing it in a proper form.
The problem with 'the proper form' part still remains, though, since it's so hazy a text type in my Country and rules differ even from a Department to the other (like, in the Italian Department they use a set of rules, in the English department they use another) but I guess I'll just have to try a less personal, more impersonal approach and see if this what was she meant when she told me to reformulate my sentences and adjust my style.
I was so angry and confused I didn't even stop to think first. I'm sorry.
Uhm, I should also mention that italian universities don't use syllabus and guidelines; usually a programme for an exam looks just like a huge list of books with a very hazy header which states the general purposes of the course, from which the students are left to draw their own conclusions.
This applies to everything we study.
I guess what confused me is that right now I'm studying how to write different kinds of papers for an Italian language exam. Last year I did the same with a philosophy exam. Both used the Italian approach, which differs from the UK and American ones. But in my earlier years I also studied how to write an essay the UK way, for my English language exams.
It's likely my teacher prefers the UK approach over the Italian one, since it's an English Lit exam, but I just went and applied the Italian approach, which is usually more rhetoric and personal and puts more enphasis on the writer's ability to persuade the reader than on the actual data. It just came more natural to me since I'm studying it right now (I'm going to do the Italian language exam in parallel with the English Lit one).
Now I'm gonna retrieve my old coursebooks and notes on how to write an essay from when I did my second-year English language exam and adjust the paper to the rules I applied back then to the paper I had to write for the writing skill assessment test. It's probably the closest form of guidelines I could find in a Country that thinks guidelines are superfluous appendixes (and this applies to academic circles and teachers too).

PS

As much as I'd love to ask my teacher for advice, in her last email she told me not to write to her anymore because she's going on vacation, that she's going to proof-read the essay only once, to work on my paper in the meantime and the next time I send it to her she'll grade it - end of the story.
Maybe I misinterpreted it but it sounded to me much like "Don't bother me" and "You're on your own". She was kind enough to tell me the draft I sent her needed to be reformulated and that it was too personal, though.
So that's why I thought to look for ways to write an essay (which I did) and ask if I could implement my personal opinions into it.
As I said before, I did not thought of retrieving past courses materials, but she was probably taking for granted we student would use those for reference.