One option is, on the mailing tab, Select Recipients in the mail merge area, then choose Outlook Contacts – this is a bit cumbersome for one contact though…. tbh, i don;t know of another way.
your boss may be referring to the address book icon. Once you add this icon to the toolbar you can click and select contacts from global address list or your personal contacts. Selecting the contact adds it into your document. To add the icon go to Office button/word options/customize and select all commands and look address book. Hope that helps.