1. take notes. notes are facts, quotes, or ideas, often compiled into simple bulleted lists. having references to the source material is invaluable. markdown is great for this.
2. comment on the notes and re-sequence them and the associated comments into a sensible progression of ideas.
3. take the expanded notes and comments and weave them into a cohesive narrative.
4. edit. have a friend read it and give you honest feedback. re-edit. you've written a lot, and you can afford to be ruthless when you're cutting the essay back down.
5. publish. your essay is a gem, don't be bashful!