Right-click an event, choose Pitch Shift from the shortcut menu, and choose a setting from the submenu:

Up	Shifts the selected event up one semitone.
Down	Shifts the selected event down one semitone.
Reset	Removes any pitch shifting that currently exists in the event.

You can also use keyboard shortcuts to quickly apply pitch shifting to selected events.

Pitch down 1 semitone	Keypad - -
Pitch up 1 semitone	Keypad + =
Pitch down 4 semitones	Shift+- Shift+Keypad -
Pitch up 4 semitones	Shift+= Shift+Keypad +
Pitch down 1 octave	Ctrl+Keypad -
Pitch up 1 octave	Ctrl+Keypad +
Reset pitch	Ctrl+Shift+-/= Ctrl+Shift+Keypad +/-

When you are ready to continue, click the Next button.