On your School Stream dashboard navigate to the Users tab (More -> Users) in the left-hand menu bar.
Click "Add New".
In the 'Add New User' section, add a username (lowercase alphabetical letters only).
Enter the user's email address.
Select the desired Role. Here's a link to the roles.
Click "Add New User" to confirm the new user.
Once the new user confirms their account via the email link they will appear in your user list and have access to the dashboard.
Well done. You've just added a new user!