The introductory paragraph is the first paragraph of your essay.
It brings in the main idea of your essay. A good opening paragraph captures the interest of your reader and notify why your topic is important.
The supporting paragraphs are the main body of your essay. In these paragraphs you discuss your main idea. You should list the points that develop the main idea of your essay. Each supporting point should be placed in seperate paragraph with its supporting sentences and those sentences should based on facts, details and examples.
The final part of your essay is the summary paragraph which comes at the end of the essay. You explain all the ideas in the supporting paragraph and make a conclusion of supporting paragraphs in the summary paragraph. By reading only the summary paragraph reader should understand the whole idea of your essay.