Huawei P9 - Manual (Page 5)

Fingerprint identification
A unique fingerprint is the safest key.
You can use your fingerprint to unlock a file safe or app lock,
take photos, unlock your screen, answer calls and stop
alarms. Safety has been made easy with fingerprints.
Touch Settings > Fingerprint ID > Fingerprint
management and follow the onscreen instructions to enroll
your fingerprint.
When enrolling your fingerprint, make sure the
fingerprint sensor and your fingers are dry and clean.