OS X Mountain Lion: Set up parental controls
As a parent, you want your kids to have a safe and happy experience on the computer. Your Mac helps you keep watch. With simple settings in Parental Controls preferences, you can manage, monitor, and control the time your kids spend on the Mac, the websites they visit, and the people they chat with.
Before you can set up parental controls
Add each child as a user of your computer, and turn on parental controls for the user.
Limit apps a child can use
To limit which apps your child can use and specify the age rating for apps they can open from the App Store, click Apps in Parental Controls preferences.
Limit Internet access
To control which websites your child can visit using Safari, click Web in Parental Controls preferences.
Limit Game Center, Messages, and Mail contacts
Limit computer time
To regulate when your child can use the computer, click Time Limits in Parental Controls preferences.