In the Calendar, you can only assign a responsible party to tasks and appointments.
Events do not have the ability to assign a team member.
All Calendar items can have participants.
To assign a task or appointment to an individual on the team, choose their name from the "Responsible Party" dropdown list of eligible team members.
The responsible party will be notified via in-app message and email that they have been assigned a calendar item. They will either need to accept or decline the invitation; if declined, the person that created the task/appointment and the people that are "Participants" will be notified.
You can change your notification settings in: Profile