The numbers on the fingers show which fingers should be used to press down the keys as shown in the following fingering diagram.
The black numbers in the white keys here show you which finger to use to press down each key. If you are ever unsure of which finger to use for a particular note, you can always refer back to this diagram.
Left Hand Fingers
A white number on a black key tells you to press and hold the key down with the finger indicated. To finger the note E, hold down the first finger and thumb of your left hand as shown in the diagram.
Right Hand Fingers
Make sure your right hand is below your left. When fingers are not being used for a note, make sure the tips of the fingers hover near the keys ready to press them down when required