The basic structure of an informal outline relies on the main headings, such as the introduction each of the prominent points or ideas, and the conclusion. Using Roman numerals (such as I, II, III and IV), set up each of the most important ideas within the presentation or essay. For example, a paper about the different combatants during World War II may be divided into: I. Introduction; II. The Axis; III. The Allies; IV. The Others; and V. Conclusion.
Using the "Tab" key in Microsoft Word, you can change the level and indentation of each line. Conversely, pressing "Shift" and "Tab" decreases the level and indent. In these subheads, usually labeled with letters, you can be more descriptive and add details about ideas within the main points that you wish to discuss. The more detail in these subheads, the easier it will be to write the body of the paper.
Under the "Format" menu in Microsoft Word, you can change the settings for the indentation. Often, increasing the amount each level of the outline is indented makes for a cleaner look and allows for easy differentiation between the various ranks. Outside of the formatting menu, you can adjust the indentation sliders on the horizontal ruler to tweak the indent for each line of the outline.
For an even easier, pre-setup outline, use the templates available in Microsoft Word, which are available whenever you begin a new document. Templates already have formatting and structure, leaving only the language to be filled out, which makes the process of creating the outline easier. A wide variety of templates for informal outlines are available on the Internet, and Microsoft's website has many outline templates for Microsoft Word.