eNotes editors cannot write your essay for you, but I can give you some pointers which might help.
The five-paragraph essay form is relatively easy. Make sure to restate the subject in your thesis statement. Such as...
Brutus was generally successful at separating his public and private sides throughout the play, with few exceptions.
This tells your audience what you are writing about, but also gives you the flexibility to allow some room in studying Brutus' character in that he may have tried to separate the two, but was not always successful—if you see evidence of such.
The next three paragraphs are the body of the essay. Begin each with a topic sentence that introduces what each paragraph will be about. Once you state your subtopic (i.e., how Brutus successfully separates these two sides of his life), support this with specific examples that prove your point. This is essential: a general statement must be supported with proof from the play. This shows your understanding of the play and your ability to organize what you know on paper.
The second body paragraph might indicate the instances you have found when Brutus was not successful in separating these two parts of his life—with supporting examples. The third body paragraph could reflect how Brutus' ability—and inability—to do so impact his actions and, ultimately, his fate.
The final paragraph is your conclusion. Do not introduce new details or new supporting evidence here. This is where you pull your points together in a general way. You can make a general statement about how difficult it can be to control the differing aspects of one's life, and how the inability to do so indicates (if there is evidence of this) a person's inability to live separate lives. In other words, Brutus' inability (if this is your argument) to keep his public and private lives separate may be the result of a his conscience. For what he is in private (you may say) is much who he is in public. You could then state, in general, how it ultimately affects his life and keeps him from finding peace and satisfaction with his choices or decisions. Keep it general, though. And don't restate details from the body.
You should use quotes to support your opinions. You may want to speak to your teacher if there is time—but with a five page essay, I would not use more than two or three short quotes. These should be indented from the rest of the paper if they are two or three lines long, and each should have some kind of "Shakespearean" notation. For example, if you use a quote from Act Two, scene one, lines 13 through 15, it would look like this:
How that might change his nature, there's the question.
It is the bright day that brings forth the adder
And that craves wary walking. (II.i.13-15)
As you write, stay focused on your topic. Stop at the end of each paragraph and check. If you ramble, you will lose focus and lose points. It may appear to your teacher that you don't know what you are writing about.
Make sure you access eNotes sources on writing the five-paragraph essay; the character analysis of Brutus; the themes; the summary; and, the eText of the actual play. In these sources you will find references to Brutus being torn between two schools of thought—between "two visions of the future," for example.
Also, make sure you do not plagiarize, but put everything in your words—don't even copy the structure of the sentences you use.
Take your time. Edit, edit, edit. And proofread several times.