Whether you're currently logged into the Parent Portal or not, there is a "Reset Password" item in the top menu which will allow you to initiate the password change process.
Clicking the "Reset Password" link will prompt you to enter your Hillbrook Parent Code and submit.
This will generate an emil to your primary email address which will contain a link you can use to choose a new password.
Click the link, enter your new password twice and submit.
This will set your password to the new value and send you a confirmation email.
You'll then be able to log into the Parent Portal and access all services with your new password.