1. Go to the Account page in the top right drop down menu.
  2. Enter a team member’s email address in the text field under the Invite Your Team heading.
  3. Click the Invite Team Member button to email them an invitation to contribute.

They will appear as pending until they click the link in their invitation email and choose a password. You can set their User Permissions to Reader, Editor, Publisher, or Admin by clicking whichever permission you want to give them.