Your question is an important one. Let me give you a few points to get you started.
First, it is important not to think of writing as a simple formula. So, in this instance, the three articles do not necessarily constitute three paragraphs. Writing is more thematic in nature.
Second, you need to have a thesis statement. In short, a thesis is the main point of your essay or what you intend to prove. So, if you are reading three articles on technology, then your thesis might be, computers make life easier.
Third, you will use the articles to support your point. In other words, the articles supply your arguments, which supports your thesis. So, for example, you might argue that computers make life faster, more organized, and more efficient.
Keep in mind that all your points support your thesis.