How do I adjust a contact's details?

On the Contact list screen, go to the contact you wish to edit, click on the 'hamburger' icon on the right side and choose Edit contact details.

Or click directly on the Edit icon in the contact widget.  

In both cases, the contact details are shown and you can add all relevant information. Even the data in the left sub items:

When done, just click on Save and SpinOffice processes the changes. The popup will close.