No one here is going to write your essay for you; it is your assignment and your teacher expects you to do your own writing. Submitting work which is not your own is plagiarism (cheating), and I'm confident you are not interested in cheating. What I can do for you is offer you some help to collect your own thoughts on the subject and offer you a resource or two which I'm certain you will find helpful.
First of all, you need to know what each of these men believed. I assume you have studied them, at least to some degree, and you know that they are generally more different than alike. While both of them believed in the existence and supremacy of natural law, Hobbes disagrees with most of the other natural law theorists as he sees man as an anti-social being rather than a social being (which is what Locke believed).
Given their differences, you will want to select the few points of comparison and then three or so significant differences between them. Once you narrow down your issues, you will have to determine your point of view, something essential to an argumentative essay. In other words, you will have to make a case that one is better (or more likely to be true) than the other. I have attached a very helpful site (below) which provides a chart outlining some of the key issues on which the two men both agree and disagree.
The comparison and contrast between the two theorists might look something like this:
Hobbes favored unlimited power for the state, and he favored it for the purpose of ending all conflict and contention. He saw all non-state society as simply bad happenings that should be suppressed.
Locke argues that government is legitimate, but only legitimate in so far as it acts within the limits of this implied contract.
Once you determine the issues you want to write about, you will have to write a thesis (purpose) statement and an outline. The outline may seem like a bit of a nuisance; however, if you create a good outline, you will be able to write much more quickly and efficiently.
I have also attached an excellent eNotes site (also below) which will walk you through the steps to write an effective argumentative/persuasive essay. The two most important things are first, to get and stay organized, and second, to have and maintain a clear position (for or against something) by using persuasive language.