To set options for Siri, go to Settings > General > Siri. Options include:
Turning Siri on or off
Voice gender (may not be available in all areas)
My Info card
Raise to speak
Prevent access to Siri when iPhone is locked. Go to Settings > Touch ID & Passcode (iPhone 5s) or Settings > Passcode (other models). You can also disable Siri by turning on restrictions. See Restrictions.