STEPS
TOOLS
Click on Start Button
Click on Control Button
In the Control Panel window , click User Accounts and Family Safety. Then click Parental Controls. 
  In the Parental Controls window, under Users, click Child.  
In the User Controls window, under Parental Controls, click the On, enforce current settings option. 
 Windows 7

How to set parental control on your computer

Setting Up Parental Controls Using the Control Panel, display the Parental Controls window. Select the user named Child, and then change the Parental Control option to On, enforce current settings.