For an epilogue or a prologue, you have to make a new chapter. Then, in the chapter title, you can write Epilogue or Prologue, or give it another name if you’d prefer. That makes it look like this:
From there, you can then click on where it says (in this example) ‘Chapter 7’. This will turn off chapter numbering, leaving you with this:
See how the ‘Chapter’ is faded?
Turning off the chapter numbering means that your manuscript chapters will then start at Chapter 1 after the prologue, and that your epilogue won’t have an ugly chapter heading you can’t get rid of. The end result will be like this:
Hope this helps