The emphasis of the instruction was on personal safety. Just as you would not walk up to strangers on the street and divulge personal information, nor should you do so online. Any online interactions should be approved by a parent or responsible adult; anything you write, text, or post online should be something you could share with a parent or grandparent; any words or images encountered that make you uncomfortable should be brought to the attention of an adult immediately.
On its netsmartz.org website, the National Center for Missing and Exploited Children has some useful tools to help parents engage in meaningful conversations with their children. The Common Sense website evaluates all types of media and provides some great resources for parents under the Parent Concerns tab.
Both of these websites are linked on the Media Center's Research Symbaloo, located at the bottom of the Media Center webpage.