To write a good argument, you need good facts. Before you can write a good essay, you need to be well-informed on your topic. Once you have the facts, you have to know how to use them. There are many persuasive techniques, but the best ones in business are to use examples and anecdotes. Use hypothetical products and numbers and situations. This will help to drive your point home.
When you are writing an argumentative or persuasive essay, you have a position you are advocating. For example, you might take a position on capital punishment. You might inform your audience that you oppose capital punishment. That is the thesis for your essay.
But is it enough to tell your audience you oppose capital punishment and not say any more? Of course not! No reader is going to change his or her mind on just your say so. You need to support your position. How you support your position depends on the subject you are discussing and the position you take. Each time you write an argumentative or persuasive essay, there will be different kinds of evidence.
What kinds of evidence are available to you? You can discuss specific incidents that you know about or discover through your research. We call that anecdotal evidence. If you were writing an essay arguing that capital punishment should be abolished, you might present a story about people who were found to be innocent after they were executed. You can present statistics to support your thesis. That is called statistical evidence. For example, the statistics might show that capital punishment does not decrease crime. Sometimes you can use a hypothetical situation to make your case or use logic. We can also use visuals to support a position, for example, a picture or a graph.
Since I do not know what topic or position you are going to write about, I cannot give you examples that will help your specific situation. But I do hope that this helps you to see the kind of evidence you need to support a position.
Good luck to you.
Being argumentative and persuasive are two different things. Argumentative implies proving that you are correct while the other person is wrong. In many cases this can have the opposite effect of persuading. Two famous cases of ill effects of being logically correct and yet failing to persuade are provides by Galileo and Socrates.
Coming to the information part, it is quite clear to have knowledge of the subject you are discussing. The more information you have better it is. But it is no good to flood other person with tons of information. You should only provide such information that the other person will understand and appreciate. To do this it is also necessary to know something about the person you want to persuade. And, many times, the best way to find this is to ask him or her - first try to understand and then try to be understood.