To redact is to arrange or edit text in a written document. Don't get too attached to every word in your rough draft; your teacher will expect you to redact it before handing in your final paper.
Redact refers to any kind revising or editing that makes a document better, usually for publication. When you see the prefix re-, you know the word is going to refer to something either being done again or retracted. You can think of redact as redoing writing or taking back some of what was originally said. You'll often see the word redact being used with the prepositions in or into. You might take several documents and redact them into a single one.