Headers are the lines that show up at the top of the page and footers are at the bottom.   They tell you something about what you are reading. 

To put in a header or footer choose View/Header and Footer.  The cursor will autmomatically point inside a dotted-line Header box.  To change to a footer box choose the icon on the Header and Footer tool box.

You can choose which side of the page you want the header or footer aligned and if you want it only on odd or even pages.

Within the Header and Footer tool box are icons that allow you to put the page number , date , and time on the page.  You can also put in page numbers by choosing Insert/Page Numbers and you will get a page number tool box shown below.  Choose a position and alignment and then click OK.