Instructions
Power on the Nintendo DSi and select the System Setting menu on the main screen.
Scroll through the available menus until the Parental Controls menu is displayed, then select it by tapping on the menu with the stylus.
Select "Yes" if prompted with the "Use Parental Controls?" option. This prompt will not be displayed if Parental Controls are already enabled.
Read the Parental Controls information screens, then tap on "OK" to continue.
Choose a 4-digit PIN when prompted and then tap "OK" to continue. Enter the PIN a second time to confirm and then tap "OK" to continue.
Select a secret question in case your forget your PIN. Follow the prompts to enter and save the answer to the secret question, then tap "OK" to continue.
Answer the questions displayed on the DSi to continue the Parental Controls setup. The answers will depend upon personal preferences.
Select "Yes" when prompted with the "Restrict the use of the Nintendo DSi Browser?" option.
Answer the remaining questions according to personal preferences, then select "OK" to confirm all selections.
Parental Controls are now enabled and anyone using the DSi will be prompted to enter the previously selected PIN when he attempts to access the Internet with the DSi browser.