Depending on your paper rubric, class guidelines, or formatting guidelines, you may have to organize your paper in a specific way. For example, when writing in APA format you must organize your paper by headings including the introduction, methods, results, and discussion. These guidelines will alter the way you craft your outline and final paper.
To draw a parallel, a lawyer researches and reads about many cases and uses them to support their own case. A scientist reads many case studies to support an idea about a scientific principle. In the same way, a history student writing about the Vietnam War might read newspaper articles and books and interview veterans to develop and/or confirm a viewpoint and support it with evidence.
Any information that doesn’t fit within the framework of your outline, and doesn’t directly support your thesis statement, no matter how interesting, doesn’t belong in your research paper. Keep your focus narrow and avoid the kitchen sink approach. (You know, the one where you throw in every bit of interesting research you uncovered, including the fungal growth in the U-joint of your kitchen sink?) Everything you learn may be fascinating, but not all of it is going to be relevant to your paper.
The thesis statement is a 1-2 sentence statement at the beginning of your paper that states the main goal or argument of your paper. Although you can alter the wording of your thesis statement for the final draft later, coming up with the main goal of your essay must be done in the beginning. All of your body paragraphs and information will revolve around your thesis, so make sure that you are clear on what your thesis is.