It is a part where you have a power to write your point of view and make your readers except it using different methods. The final goal is to persuade your reader that your opinion is correct and your understanding of the issue is clear.
If you really want to persuade other people to believe in your statement, it is not enough only to write about it.
There are several topics one could choose for an argumentative essay.
One could start by looking in newspapers and magazines as to what hot topics are being discussed at the moment, or it could be something they feel quite passionate about.
You will never create a masterpiece if you do not believe in what you are writing about.
The main task is to support your position in every sentence, not letting your reader doubt.
When writing a narrative you simply tell your audience about a fact or an event, i.e., sharing information.
An argumentative essay aims at stating the author's opinion on something and trying to get the audience to agree with it.
And every sales manager or marketing specialist try to focus on needs, which stay not satisfied by other companies.
In your case, your reader feels a lack of information, so satisfy his need and give him the sufficient evidences to prove your point of view.