1. Log in to your Wordpress admin interface
2. Find Appearance > Editor in left navigation menu.
3. To the right of the editor's area find the "Theme Header" template
4. Ensure this file is writable on your filesystem.
5. Copy the DeskPRO widget code snippet from the Admin interface of DeskPRO (Admin > Chat > Site Widget & Chat)
6. Insert this in Wordpress before the closing "</head>" tag