Nintendo have some great tutorials on how to enable parental controls on Nintendo games consoles including Wii, Wii U, 3DS and DSi.
Depending on the console, the tutorials show you how to control or block access to some or all of the following:
- Age restricted games
- Access to the internet browser built in to the console
- Online interaction with other people
- Access to the Miiverse (Nintendo Social Network)
- Adding friends
- Deleting content
- Changing internet settings
- Restrict viewing of video content
- Shopping services
- Online exchange of details and images
How to do these can be found clicking on the following link: Using Parental Control Settings on Nintendo Systems