If you wish to leave a message for someone, sign in to your profile, locate the person you wish to leave a message and go on their profile page. Type in your message in the field below Post a message for [name of person]. Click post update when you are done.
To see the message you left for that particular parent, go to All Updates under the All Recent Activity tab.
If you have any questions about leaving a message for another user, feel free to contact Support here.