Organizing ideas takes time. Many students have learned, either in high school or in college remedial writing programs, that an acceptable essay consists of an introduction, three or four points in a "body," and a concluding paragraph. For short, two- or three-page papers, that organization works just fine, but for other courses, (and in life) most students will have to write papers that are five, ten, twenty-five pages, or even longer. Organizing such longer papers into simply three or four "body" parts will not work very well. If you want to do well in writing longer papers, you need to learn

1) how to break bigger topics into smaller sub-topics (or group smaller topics into bigger ones), and 
2) how to reflect that organization in your writing.

To assist you in learning how to do this, I expect you to number the paragraphs in your papers and to write what I call "paragraph outlines." 
     A paragraph outline is simply a formal outline plus an indication of which paragraphs go with which sections of the outline. You will make this indication simply by writing the numbers of the paragraphs which correspond to each section of your outline to the left of that section in your outline: 
 

Except for your introduction and conclusion, the words in your outline should appear in the first sentences of their respective sentences. For example, the second paragraph of  the preceding paper might begin with "There are many free editing programs that you may already have or that you can easily download from the web." The first sentence of the fifth paragraph might begin "Once you have some text in your document, you will probably want to add graphics. The easiest way to begin to do so is to find some free graphics on the web." Note that in this case the first sentence introduces the major topic (IV), and the second sentence moves right into the sub-section (IV.A.). Although sometimes two or three short sub-sections might be combined into one paragraph, generally speaking every line in your outline should have the potential of being an entire paragraph (or more) in your essay.
     As you plan your essay, your tentative outline should already give you an idea of which section(s) of your paper will have sub-divisioins. In effect, your outline will reduce longer papers into an organized collection of shorter ones.