Your BODY paragraphs all need to begin with a TOPIC STATEMENT (aka, CLAIM). This topic statement then should be followed by with EVIDENCE (aka, SUPPORTING FACTS). ELABORATION (aka, REASONING) should follow. Finally, each body paragraph should have a concluding statement that summarizes the paragraph and/or leads into the next topic/body paragraph.
Topic Statement - A topic sentence essentially tells readers what the rest of the paragraph is about.
Example: There were many contributing factors that caused The Black Plague to spread throughout Europe.
Evidence (Supporting Facts): Facts, statistics, quotations, dates/time period, first-hand accounts, expert opinions from historians, etc.
Example: Unknowingly, traders brought rats carrying the disease to Mediterranean ports in 1347.
Elaboration (Reasoning): Phrases that add details, anecdotes, examples, perspectives from different historians, etc.
Example: People during the Middle Ages didn't realize that fleas from rats could spread the plague; and therefore, they did not concern themselves with controlling the infestation from pests. Today, the presence of rodents in a public restaurant, for example, would be considered a public health threat.
Closing Statement: A summary of the information you just presented and a tie-in to your next topic
Example: All of these factors caused the plague to spread rapidly and causing many in Europe to die at an alarming rate. (Next topic will be about the numbers of deaths in Europe).