When typing your paper in a standard word-processing program, use your computer's mouse to place the cursor right after the phrase you wish to footnote. The actual footnote number goes after the final character and punctuation of the phrase you are marking for citation. Note that footnote numbers go after all punctuation except dashes. In Microsoft Word 2007, click the "References" tab at the top of the page, and look for "Footnotes." Click "Insert Footnote." You can do it more quickly by typing ctrl+alt+F.
Your cursor should jump to the bottom of the page with the appropriate footnote number next to it. Start your footnote by naming the document -- like the Constitution -- in quotation marks. Put a comma after the document name. It should appear as "The Constitution of the United States," .
Write "Article" with an uppercase A and write the article number you're citing. Place a comma after the number. It should say: "The Constitution of the United States," Article 1, .
Write "Section" with an uppercase S, and write the section number you're citing. Put a comma after the number. It should say: "The Constitution of the United States," Article 1, Section 8, .
Write "Clause" with an uppercase C and write the clause number you're citing. Put a period after the number. It should say: "The Constitution of the United States," Article 1, Section 8, Clause 5.
When you're finished writing your footnote, use your mouse to return the cursor to the main body of your paper.