Welcome!!!!
It certainly is wise not to disclose personal information over the internet.
I think the laws you are referring to are sites that collect personalinformation (starting a yahoo account for example). It'ssimilar to the Privacy Act Issuances notices that you often receive inthe mail,and does not apply to a person willingly disclosingprivateinformation on a public forum or website (which can bea dangerous practice, especially for youth). It is unwise(but not illegal) for a person under 18 to disclose personalinformation -- a reason why parents must be aware of their child'sactivities on the internet.
To learn more about the Childrens Online Privacy Protection Act (COPPA) and how it applies to internet use for children . . .
http://www.ftc.gov/privacy/privacyinitiatives/childrens.html
http://www.ftc.gov/opa/2001/10/slidingscale.htm
Pam