Simply twist the knob that's located on the turn signal lever (left side of the steering wheel).
The switch on the left should always be left on AUTO as shown below. This means that the headlights will turn on whenever it gets dark. They will turn off automatically when you drive into a bright area.
To activate the high-beam, just pull the same lever here towards you for a quick flash and push it away from you to switch on high-beam mode.