1. Find "Touch ID & Passcode"
Tap Settings.
Tap Touch ID & Passcode.
2. Add fingerprint
Tap Add a Fingerprint....
Follow the instructions on the display to add a fingerprint.
Tap Continue.
Key in a phone lock code of your own choice.
Key in the same phone lock code again.
3. Select settings for Touch ID
To use Touch ID as phone lock code:
Tap the indicator next to "iPhone Unlock" until the function is turned on.
To use Touch ID to authorise iTunes or App Store purchases:
Tap the indicator next to "iTunes & App Store" until the function is turned on.
4. Return to the home screen
Tap Settings
Tap the Home key to return to the home screen.
5. Use Touch ID
Touch the Home key to scan your fingerprint.