On Account Settings Tab under Add Account Member you can add new users to your account by adding an email and selecting a role of Administrator or Editor. Administrator user can perform every action available and Editor users can only create, read and update.
Once a new member is added, an email will be sent inviting them to join. The invitation will expire three days after the email is sent.
After a new user is added new table will shop up below showing invited users. You can also cancel the invitation at any time before user has accepted it.