Create or click on an event that you would like to associate with a matter or contact.
Near the bottom of the window, select 'More options':
Any previously created contacts and matters will be available in the pulldown menus. Select the contact and/or matter you wish to associate with this calendar event:
Add attendees from your list of client contacts or team members:
Add optional 'Description' or 'Location' information as needed
When finished, click 'Save & Continue'