If you already know how to:

• Insert page numbers in the header or footer
• Restart your page numbering
• Create different sections with different headers and footers inside the same document (ex: first 3 pages have no header and all pages after the third have the same header)

then you can just click the moodle complete item. Otherwise, do the following: 

If you are using MS Word: 

1. Watch this
2. Or Read this (and maybe choose to watch the video inside it)

If you are using Open Office Writer:

1. Watch this