Office 365 (Apple Contacts 10.9) - Editing a contact
This document explains how to edit a contact in Apple Contacts for OS X 10.9.
Open Apple Contacts, and type the name of the contact you wish to edit into the search field at the top of the middle column. If the search finds more than one contact, left-click on the one you want to edit. Once you have selected the contact you wish to modify, click Edit in the bottom right.
The right-hand column with the contact information will become a form within which you may add/edit the information you like.
Once you have finished modifying the contact info, click Done to save your changes.