The following screenshots are taken from an iPhone, however, I think that most Apple devices are similar and should have similarities between their settings & parental restrictions.
Firstly, you will need to enter the “settings” for the phone which can be found on your iPhone's homescreen (somewhere, depending where you keep it):
Once inside, you will see a list of different things to customise. I would suggest turning off the “Location Services” if the device is for your child as if they use apps such as Facebook etc, everytime they update their status, it'll also update their location.
Next, go into the “General” settings:
Inside the General settings, you can choose to put a “Passcode Lock” on your phone (which will be handy if your child is just using your device now and again and you don't want to give them access all the time). A passcode consists of a four digit number you can choose yourself to stop others from gaining access once the phone has been locked.
Note: If you have one, make sure your passcode is easy to remember but difficult for others to guess i.e. don’t use “0000”, “1234”, your birth year or your child’s as these will be easy to guess (especially by your child!).
Next go to “Restrictions:
The Restrictions menu offers you the chance to add parental controls onto the device for things like the internet browser (Safari), Youtube, installing and deleting apps etc. It also lets you control what media can be played on the device. For example, if your child wanted to use your iPod to listen to their music, but you also had explicit music on there too, you can select an option that will prevent any explicit songs from playing.
Most game applications on the iPhone (and probably iPods and iPads) can be played online with another person. The other player is selected through the “Game Center” at random and you can have the option to add that player to your friends list to play with again if you choose. To my knowledge, I don’t think you are able to converse with friends on the Game Center as there are no chat functions but if you wish to turn this option off anyway, you can also do this in the Restrictions menu:
I think I’ve covered the majority of the settings for the iPhone. If I have missed anything out then please leave me a comment as you’ll be educating me and anyone else who sees this post!