Briefly lay out your general idea and specific thesis; explain to your audience why your work matters and why they should read it. Your introduction should be as informative and inviting as possible to engage the reader's curiosity and help ensure they give proper thought to your work.
Although these terms address different concerns, they are often combined to create a narrative. Historiography refers to an assessment of the existing literature relevant to your own work, which is useful for explaining how your work refutes, reinforces, or otherwise fills in a gap left by previous authors. Methodology is where you explain what you looked at and how you approached your paper's topic in order to reach the conclusions that you did. This is done to make your research process transparent to promote credibility.
The meat of your paper and the longest section. Dig deeper into your argument and present as much evidence as you need to make your point.
Sum up your argument and leave the reader with a distinct understanding of why they read your essay and what they should remember from it. If the introduction tells the reader what they are about to learn, the conclusion takes the last opportunity to drive that point home.
Assuming you don't use footnotes or end notes, you might add a section for notes at the very end of your essay. Many authors work these into their references section, but just as many authors have a separate bibliography that provides a list of other works you consulted, cited and/or would just like to direct the reader to for further information.