Changing your Exchange password is done from the Outlook Web App, available at http://owa.controlnetworks.com.au. Log in with your exchange email, eg.
mike@controlnetworks.com.au and your current password.
Once you have been logged in, click options in the top right-
Secondly, click settings on the left and choose the password tab. Enter your current password, followed by your new password twice. Finally, click save. You may be prompted to log back in using your new password.