Click the "Insert" menu or button in the word-processing program on your computer.
Change the options in the window that pops up to show page numbers on the top right.
Save changes and exit the pop-up window. A number should appear on the top right corner of your page.
Open up a header on the top of your page. Type the phrase "Running head:" in the header, followed by the title of your paper in capital letters. For example -- Running head: HOW TO FORMAT A HEADER IN APA STYLE