These two surfaces help the aircraft to be steady during flight, and helps you maintain a straight path through the air.
You can compare the fin or vertical stabilizer with the keel on a ship.
The rudder is attached to the back of the vertical stabilizer and can be used to move the nose of the airplane to the left or right.
When performing a turn, in a proper way you need to apply some rudder.
The elevator is attached to the back of the horizontal stabilizer.
You use it to move the aircraft up and down.
Pitch the aircraft up and down.