Family members will receive a secure email invite from their child's educator/teacher, click the 'Get Started' link in that email and in the web page that opens, create a new username and password that you can remember and click 'Signup'.
If you have multiple children, 'Signup' with the first email invite and with the subsequent invites, click the Get Started 'Link' and in the web page that open click Link Children using your username and password from the first child.
Below is a sample email invite...
And the web page that opens...