It is easy to write a short article. First thing is you need to pick up a topic that you are very much familiar with it. This will help you to write most important information about that topic. If you are picking up a topic that you do not know much about it, you will not be successful in writing a short article on that topic.
Once you have your topic, think about most important facts about that topic. Think about how your information can be useful to readers. Think about the best you can tell about that topic. These information will help you to create the article body content.
Article can start with a introduction which will cover in first paragraph. You can put your article body content in second paragraph. Third paragraph can be the conclusion. You can close your article with a most important view point about the topic or your personal view about the topic.
Thus, you have create your short article.