Go to the References tab. Select Insert Footnote or Insert Endnote option. Write the Footnote and Endnote. Finish editing your document so that you know where to enter the Footnote or Endnote.
Place your insertion point where you'd to annotate, and then click the "Insert Endnote" button on the "References" tab of Word's Ribbon. Just like with footnotes, Word attaches a superscript number containing an endnote.
This tutorial shows how to insert footnotes and endnotes in Microsoft Word. Plus, the bonus section at the end explains three benefits of using Word’s footnote and endnote tools.