To determine whether you want/need to comply, read here.

At Admin Panel -> Settings -> Switches, the "COPPA compliance" switch activates a checkbox on your registration page. The box asks registrants to confirm that they are at least 13 years old, or to send in a parental consent form. The registration will not go through until it's checked. If they click for the info page they're given an opportunity to read your privacy policy, which is also activated by this switch (COPPA requires a privacy policy).

You'll need to edit the COPPA template to specify your contact details to allow people to send in the parental consent form. Of course you'll also want to customize the privacy policy. Go to Admin Panel -> Themes -> Manage Templates and find the Privacy Policy template there.