Create an appendix

Put your cursor at the end of the document, and then select Layout > Breaks > Next Page.

On the Home tab, select the Styles pane.

In the Styles pane, select New Style.

Name the new style Appendix.

At the bottom of the dialog box, select Format > Numbering.

In Bullets and Numbering, select Numbered, and then a format other than None.

Select Customize.

Choose a Number style, for example: A, B, C, ... 

In the Enter formatting for the number field, carefully insert your cursor before the character that's highlighted in gray.

Type the word Appendix followed by a single space.

After the letter highlighted character, type a colon if you'd like the style to include a colon (like Appendix A:) 
Note: You can see a preview on the right. 

Select OK.

At the bottom of the dialog box, select Format > Paragraph.

Under General, for Outline level, choose Level 1. This displays the new Appendix style.

Select OK twice.

The new Appendix style will get applied to the paragraph at the top of the page. Type a description after the colon. For example: Appendix A: References 

Then insert or update the table of contents. Or, add different page numbers or number formats to the Appendix section.