1. View-Header and Footer-Use the slider to move to the footer.

2. Add a horizontal line. There are two ways:

(1) Select Format-Font-Underline-Then select thick or thin underline as needed-OK, and then press the space all the time, and a horizontal line will appear.

(2) Select Insert-Symbol-Select "Special Characters", use the first "long dash" and keep clicking "Insert" (or it will be faster to copy and paste after inserting a paragraph), so you can also make a horizontal line.

3. Write the page number at the bottom right: after drawing the horizontal line-press enter-then select right alignment and select "Add Page Number" in the footer option.