The specific method will depend on how the existing references are
formatted--Office Online has many different resume templates, so it's
impossible to know which one you're using. As a general matter, however, the
easiest method is to copy an existing "work reference" and paste it where
you want it, then replace the duplicate information with the new
information.
Instead of trying to modify and learn how to use that program why don't you just build it online at a site like http://resumizer.com That's where I make mine and it isn't a big fiasco to do it!