Open any app where you can type
Tap the text field to bring up the keyboard
Tap the keyboard icon in the navigation bar, if shown
Or swipe down from the top of the keyboard
Tap the current keyboard name
Select the keyboard you want to use
To add a new keyboard, go to Settings
Tap System management
Tap Language and input
Tap Current keyboard
Tap Choose keyboards
Turn on the keyboard you want
Return to the text field and select it from the keyboard switcher