You need to install Facebook in order to use it on your mobile phone. Before you can install Facebook, you need to set up your mobile phone for internet and activate your Apple ID on your mobile phone.
Find "App Store"
Tap App Store.
Tap the search field.
Key in Facebook and tap Search.
Tap GET and follow the instructions on the screen to install the app.
Return to the home screen
Tap the Home key to return to the home screen.