1. Select the New User button
  2. Enter the users email address in by Email. This is also his login name.
  3. By Name enter the users full name
  4. Mark the Active checkbox
  5. If the user also needs administrator rights mark the Administrator checkbox as well.
  6. Choose Save

The user receives an email with a temporary password. Once the user has logged in he can change the temporary password by selecting the email address in the upper right corner and choosing Change Password.